WEBVTT mathematics/basic-math/pyo
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Welcome back to Eduator.com.
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For the next lesson, we are going to go over discount and sales tax
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and how to calculate the amount of discount and how much sales tax we have to pay.
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We all have bought something that was on sale.
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We all have had to pay sales tax so this should be a little bit familiar.
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First let's go over discount.
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The discount we know is how much we have to subtract from our total amount that we have to pay.
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It is the amount of decrease; decrease is getting less.
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We are going to have to subtract from the regular price.
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Before we subtract however much we are going to be saving,
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we have to be able to figure out how to find how much we are going to save.
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Meaning if you are going to buy something,
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let's say you want to buy a soda and that soda is 10 percent off.
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How are you going to know how much you are going to subtract?
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How much less you are going to pay for that soda?
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Discount is the percent of the discount multiplied to the regular price.
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How much you are supposed to be paying for that
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multiplied to the percent will be how much you are going to save.
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To find how much you are going to be paying, your new price, your sale price,
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it is going to be the regular price, how much you were supposed to pay,
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minus how much you are going to save, the discount amount.
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Again discount is money; percent of discount, we know it is percent.
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Times the regular price; this is also money.
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The sale price, we know this is all going to be in money.
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The important thing to remember is that to figure out how much your discount is going to be,
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you have to multiply the percent times the regular price.
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All of this is going to equal this, the discount.
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Sales tax; sales tax is the amount that you have to pay based on the total cost.
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There is a percent; you have to pay a percent of that total cost.
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When you multiply the rate, that percent, with the total cost,
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that is going to give you how much you have to pay in sales tax.
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For sales tax, once you figure out you have to pay however much in sales in the tax,
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then you have to add it to your total cost.
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How much your total balance came out to, how much everything came out to, plus the sales tax.
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You have to pay that together; that will be how much you now owe.
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Again the rate, the percent, times the total cost is going to give you
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how much you have to pay, how much additional amount that you have to pay.
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That is all going to equal that right there.
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Let's do a few examples.
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A pair of shoes that regularly sell for 50 dollars are on sale for 10 percent off.
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Find the discount; regular price is 50 dollars.
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If it is not on sale, then you would be paying the 50 dollars.
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10 percent off; find the discount.
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We want to know how much we are going to be saving.
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To find the discount, you are going to multiply the regular price, the 50 dollars,
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times it by the percent of the discount; that is 10 percent.
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Remember whenever you use percents in some kind of equation,
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when you are solving with percent, you have to change it to decimal.
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10 percent in decimal, you put the decimal point at the end
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because we don't see one so it is always at the end.
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You are going to move it two spaces to the left because remember decimal is small number.
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Think of decimal as small.
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You have to make the number smaller by moving it to the left.
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This is going to be 50 times 0.10 or 0.1; remember 0.
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If it is at the end of a number and it is behind the decimal point, then you can drop it.
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That is going to equal the discount.
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50 times 0.10 or 0.1; I will just put 0.10.
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That is 0; 0; 1 times 0 is 0; 1 times 5 is 5.
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You can put a 0 there; you can put a 0 there.
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We add; it is going to be 5; 0; 0.
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How many numbers do you have behind decimal points?--we have two.
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Start at the end here; you are going to go one, two.
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My discount is going to be 5.00 which is the same thing in money.
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It is going to be 5 dollars.
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That is how much the discount is going to be.
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That is how much you are saving because again 10 percent of the regular price is 5 dollars.
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That is the discount amount.
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That is all they are asking for; find the discount; 5 dollars.
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The next example, a math textbook is 5 percent off.
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If the original price is 100 dollars, what is the sale price?
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The textbook originally cost 100 dollars; 100 dollars.
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To find the discount... they are asking for the new price.
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The sale price is the new price.
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After you take away how much you are saving, that is going to be the new price.
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Before we do that, we have to know what we are going to subtract.
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What is the discount amount?
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Discount is going to be the original price, the 100 dollars
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multiplied to the discount rate, percent of discount; 5 percent.
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Again we have to change this to a decimal.
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You can't solve anything out with percents.
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5 percent to decimal is going to be... start here.
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You are going to go one, two; 0.05.
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That is 100 times 0.05; then just multiply it; 100 times 0.05.
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That is 0 times 5 is 0; that is 0; 5 times 1 is 5.
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Here it is just 0, 0, 0; it is not going to change anything.
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We can write it in if you want; fill in the empty spaces with 0s.
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Add it; it is going to be 5, 0, 0.
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I don't have to add this; 0 in the front is nothing.
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How many numbers do I have behind decimal points?--I have two only.
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Here nothing; here two; in all, I have two.
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Start here; you are going to go one, two; place it there.
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This is going to be 5 dollars.
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Whenever you multiply a decimal by 100, remember you can just take this decimal point.
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Whenever you multiply a decimal number or any number with a number that is a multiple of 10,
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meaning 10, 100, 1000, 10000, 100000, then however many number of 0s you have
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is how many spaces you are going to move to the right.
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Because if you are multiplying, then you are getting bigger so you have to move to the right.
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That will be two 0s; it is going to go one, two.
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It is going to be 5.05 which is that right there.
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Let's say we are going to multiply this number 0.05 times 10.
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Let's say you are going to multiply it by 10.
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10 only has one 0; then you would move this decimal place over one time.
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It would be 0.5 or 0.5 if you multiply it by 10.
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If you multiply it by 1000, you have three 0s.
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You would move the decimal point over one, two, three times.
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That will be 50; that is a shortcut.
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Again that is only when you have 1 with 0s, a number like 10 or 100 or 1000, so on.
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My discount amount is 5 dollars; that is how much I am saving.
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I have to take the original price, how much I am supposed to be paying.
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The sale price then is my 100 dollars or the original price of 100 dollars
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minus however much I am going to be saving, the discount.
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My new amount, the new price that I have to pay, 100 minus 5 is 95 dollars.
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If you want to solve it out, you can change this to a 10.
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This becomes 9; 10 minus 5 is 5; bring down the 9.
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95 dollars; that is my new price.
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Let's go over sales tax now.
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A shirt cost 10 dollars; find the sales tax if the rate is 10 percent.
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Now we have to actually pay more because sales tax we have to
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add to our balance or add to how much we have to pay.
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The original cost is 10 dollars.
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To find how much the sales tax is going to be, I am going to take that 10 dollars.
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Then multiply it to the 10 percent, the rate, the sales tax rate.
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Again I want to change this percent to a decimal; 10 percent to decimal.
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Start here; you are going to go one, two; 0.10 or 0.1.
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Again the 0 is at the end of a number behind the decimal point.
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You can just drop it; 10 times 0.10 or 0.1.
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Look we can use our shortcut rule because we have a decimal
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or we have a number that is being multiplied to 10, 1 with a 0.
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How many 0s do I see here?--just one.
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I can take this decimal point; I can just move it over one space.
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If I were to multiply this number by 100, I have two 0s.
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I can move this over two spaces to the right.
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Be careful you don't move it to the left.
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If you move it to the left, you are going to make your number smaller.
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You have to move it to the right so that you want a bigger whole number.
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Again 100, you are going to move it two spaces over.
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If it is 1000, you have three 0s in 1000.
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You are going to move it over three spaces.
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You have to fill in your empty spaces with 0s.
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Let's get rid of that 100; 10 times 0.10 or 0.1 is 1.0.
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Remember I move the decimal place over once because of that number.
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It is 1.0 which is the same thing as 1.
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My sales tax is going to be 1; let me move this over.
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Give my dollar sign some room; my sales tax is going to be 1 dollar.
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That is how much I have to pay in sales tax
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for my shirt that costs 10 dollars if the tax rate is 10 percent.
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The next example, we are going to buy a CD that costs 14 dollars.
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It is not on sale even though that is better on sale.
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It has 10 percent sales tax; let's see, sales tax.
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What are we looking for?--total amount that we are going to end up paying.
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Before we figure out the total amount, we need to know how much we are going to pay for sales tax.
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The total due or the cost is going to be 14 dollars.
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Times it by the sales tax rate which is 10 percent.
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Again change this to a decimal; this is 14; this is one, two.
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That is 0.10 or 0.1; 0.10, you can just drop the 0 if you want.
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0; 0; 1 times 4 is 4; 1 times 1 is 1.
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Put 0s in those spaces; add them; 0 plus 1 is 1.
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0 plus 4 is 4; 0 plus 0 is 0; 140.
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How many numbers do I have behind decimal points? I have two.
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From here, I am going to go one, two.
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It is going to be 1.40; that is money.
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A dollar forty is how much I have to pay in addition to my 14 dollars I have to pay for the CD.
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Total due, total is going to be the 14 dollars plus the dollar forty.
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14 is the same thing as 14.00; plus 1.40.
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When you add numbers with decimal points, you have to make sure
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the decimal points are lined up, the two are lined up like this.
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All the rest of the numbers are aligned also.
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This is 0; this is 4; bring down the decimal point.
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4 plus 1 is 5; 1; bring it down.
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How much am I paying?--15 dollars and 40 cents.
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That is how much I have to pay for a 14 dollar CD if I have to pay for sales tax.
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That is it for this lesson; thank you for watching Educator.com.