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Lecture Comments (2)

1 answer

Last reply by: zoia kogay
Thu May 14, 2015 6:40 PM

Post by Corinne Lee on July 26, 2011

great vid

Discount and Sales Tax

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  • Discount: The amount of decrease, which is subtracted from the regular price
  • Discount = Percent of discount × Regular price
  • Sale price = Regular price – discount
  • Sales tax: The amount of the rate of the cost, which is added to the total
  • Sales tax = Rate × Total cost
  • Total due = Total cost + Sales tax

Discount and Sales Tax

A pair of shoes that regularly sell for $60 are on sale for 10% off. Find the discount.
  • 10% = 0.10
  • discount = ($60)(0.10)
A pair of shoes that regularly sell for $120 are on sale for 20% off. Find the discount.
  • 20% = 0.20
  • discount = ($120)(0.20)
A math textbook is 15% off. If the original price is $100, what is the sale price?
  • 15% = 0.15
  • discount = ($100)(0.15)
A history textbook is 30% off. If the original price is $150, what is the sale price?
  • 30% = 0.30
  • discount = ($150)(0.30)
$ 45
A car is 12% off. If the original price is $3500, what is the sale price?
  • 12% = 0.12
  • discount = ($3500)(0.12)
A shirt costs $20. Find the sales tax if the rate is 15%.
  • 15% = .15
  • sales tax = ($20)(.15)
$ 3
A shirt costs $65. Find the sales tax if the rate is 60%.
  • 60% = .60
  • sales tax = ($65)(.60)
A shirt costs $55. Find the sales tax if the rate is 20%.
  • 20% = .20
  • sales tax = ($55)(.20)
Find the total cost of a $35 CD with 10% sales tax.
  • 10% = .10
  • sales tax = ($35)(.10) = $3.50
  • total = $35.00 + $3.50
Find the total cost of a $65 book with 20% sales tax
  • 20% = .20
  • sales tax = ($65)(.20) = $13
  • total = $65 + $13

*These practice questions are only helpful when you work on them offline on a piece of paper and then use the solution steps function to check your answer.


Discount and Sales Tax

Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.

  • Intro 0:00
  • Discount 0:19
    • Discount
    • Sale Price
  • Sales Tax 2:24
    • Sales Tax
    • Total Due
  • Extra Example 1: Finding the Discount 3:43
  • Extra Example 2: Finding the Sale Price 6:28
  • Extra Example 3: Finding the Sale Tax 11:14
  • Extra Example 4: Finding the Total Due 14:08

Transcription: Discount and Sales Tax

Welcome back to

For the next lesson, we are going to go over discount and sales tax0002

and how to calculate the amount of discount and how much sales tax we have to pay.0005

We all have bought something that was on sale.0011

We all have had to pay sales tax so this should be a little bit familiar.0014

First let's go over discount.0021

The discount we know is how much we have to subtract from our total amount that we have to pay.0023

It is the amount of decrease; decrease is getting less.0031

We are going to have to subtract from the regular price.0035

Before we subtract however much we are going to be saving,0038

we have to be able to figure out how to find how much we are going to save.0043

Meaning if you are going to buy something,0048

let's say you want to buy a soda and that soda is 10 percent off.0051

How are you going to know how much you are going to subtract?0057

How much less you are going to pay for that soda?0060

Discount is the percent of the discount multiplied to the regular price.0065

How much you are supposed to be paying for that0074

multiplied to the percent will be how much you are going to save.0077

To find how much you are going to be paying, your new price, your sale price,0084

it is going to be the regular price, how much you were supposed to pay,0091

minus how much you are going to save, the discount amount.0095

Again discount is money; percent of discount, we know it is percent.0099

Times the regular price; this is also money.0110

The sale price, we know this is all going to be in money.0115

The important thing to remember is that to figure out how much your discount is going to be,0123

you have to multiply the percent times the regular price.0129

All of this is going to equal this, the discount.0134

Sales tax; sales tax is the amount that you have to pay based on the total cost.0146

There is a percent; you have to pay a percent of that total cost.0157

When you multiply the rate, that percent, with the total cost,0163

that is going to give you how much you have to pay in sales tax.0173

For sales tax, once you figure out you have to pay however much in sales in the tax,0182

then you have to add it to your total cost.0189

How much your total balance came out to, how much everything came out to, plus the sales tax.0195

You have to pay that together; that will be how much you now owe.0200

Again the rate, the percent, times the total cost is going to give you0207

how much you have to pay, how much additional amount that you have to pay.0212

That is all going to equal that right there.0218

Let's do a few examples.0224

A pair of shoes that regularly sell for 50 dollars are on sale for 10 percent off.0226

Find the discount; regular price is 50 dollars.0232

If it is not on sale, then you would be paying the 50 dollars.0239

10 percent off; find the discount.0243

We want to know how much we are going to be saving.0245

To find the discount, you are going to multiply the regular price, the 50 dollars,0252

times it by the percent of the discount; that is 10 percent.0264

Remember whenever you use percents in some kind of equation,0272

when you are solving with percent, you have to change it to decimal.0281

10 percent in decimal, you put the decimal point at the end0284

because we don't see one so it is always at the end.0292

You are going to move it two spaces to the left because remember decimal is small number.0294

Think of decimal as small.0303

You have to make the number smaller by moving it to the left.0305

This is going to be 50 times 0.10 or 0.1; remember 0.0309

If it is at the end of a number and it is behind the decimal point, then you can drop it.0318

That is going to equal the discount.0325

50 times 0.10 or 0.1; I will just put 0.10.0328

That is 0; 0; 1 times 0 is 0; 1 times 5 is 5.0337

You can put a 0 there; you can put a 0 there.0345

We add; it is going to be 5; 0; 0.0348

How many numbers do you have behind decimal points?--we have two.0352

Start at the end here; you are going to go one, two.0355

My discount is going to be 5.00 which is the same thing in money.0362

It is going to be 5 dollars.0371

That is how much the discount is going to be.0373

That is how much you are saving because again 10 percent of the regular price is 5 dollars.0374

That is the discount amount.0381

That is all they are asking for; find the discount; 5 dollars.0383

The next example, a math textbook is 5 percent off.0389

If the original price is 100 dollars, what is the sale price?0393

The textbook originally cost 100 dollars; 100 dollars.0398

To find the discount... they are asking for the new price.0406

The sale price is the new price.0410

After you take away how much you are saving, that is going to be the new price.0412

Before we do that, we have to know what we are going to subtract.0417

What is the discount amount?0421

Discount is going to be the original price, the 100 dollars0424

multiplied to the discount rate, percent of discount; 5 percent.0431

Again we have to change this to a decimal.0440

You can't solve anything out with percents.0442

5 percent to decimal is going to be... start here.0445

You are going to go one, two; 0.05.0449

That is 100 times 0.05; then just multiply it; 100 times 0.05.0457

That is 0 times 5 is 0; that is 0; 5 times 1 is 5.0470

Here it is just 0, 0, 0; it is not going to change anything.0477

We can write it in if you want; fill in the empty spaces with 0s.0482

Add it; it is going to be 5, 0, 0.0486

I don't have to add this; 0 in the front is nothing.0490

How many numbers do I have behind decimal points?--I have two only.0494

Here nothing; here two; in all, I have two.0500

Start here; you are going to go one, two; place it there.0506

This is going to be 5 dollars.0511

Whenever you multiply a decimal by 100, remember you can just take this decimal point.0523

Whenever you multiply a decimal number or any number with a number that is a multiple of 10,0532

meaning 10, 100, 1000, 10000, 100000, then however many number of 0s you have0538

is how many spaces you are going to move to the right.0548

Because if you are multiplying, then you are getting bigger so you have to move to the right.0551

That will be two 0s; it is going to go one, two.0556

It is going to be 5.05 which is that right there.0560

Let's say we are going to multiply this number 0.05 times 10.0565

Let's say you are going to multiply it by 10.0571

10 only has one 0; then you would move this decimal place over one time.0573

It would be 0.5 or 0.5 if you multiply it by 10.0579

If you multiply it by 1000, you have three 0s.0584

You would move the decimal point over one, two, three times.0587

That will be 50; that is a shortcut.0591

Again that is only when you have 1 with 0s, a number like 10 or 100 or 1000, so on.0595

My discount amount is 5 dollars; that is how much I am saving.0602

I have to take the original price, how much I am supposed to be paying.0607

The sale price then is my 100 dollars or the original price of 100 dollars0613

minus however much I am going to be saving, the discount.0624

My new amount, the new price that I have to pay, 100 minus 5 is 95 dollars.0630

If you want to solve it out, you can change this to a 10.0645

This becomes 9; 10 minus 5 is 5; bring down the 9.0653

95 dollars; that is my new price.0663

Let's go over sales tax now.0677

A shirt cost 10 dollars; find the sales tax if the rate is 10 percent.0681

Now we have to actually pay more because sales tax we have to0688

add to our balance or add to how much we have to pay.0691

The original cost is 10 dollars.0697

To find how much the sales tax is going to be, I am going to take that 10 dollars.0700

Then multiply it to the 10 percent, the rate, the sales tax rate.0713

Again I want to change this percent to a decimal; 10 percent to decimal.0721

Start here; you are going to go one, two; 0.10 or 0.1.0727

Again the 0 is at the end of a number behind the decimal point.0733

You can just drop it; 10 times 0.10 or 0.1.0736

Look we can use our shortcut rule because we have a decimal0749

or we have a number that is being multiplied to 10, 1 with a 0.0752

How many 0s do I see here?--just one.0758

I can take this decimal point; I can just move it over one space.0761

If I were to multiply this number by 100, I have two 0s.0769

I can move this over two spaces to the right.0775

Be careful you don't move it to the left.0778

If you move it to the left, you are going to make your number smaller.0780

You have to move it to the right so that you want a bigger whole number.0784

Again 100, you are going to move it two spaces over.0791

If it is 1000, you have three 0s in 1000.0792

You are going to move it over three spaces.0796

You have to fill in your empty spaces with 0s.0798

Let's get rid of that 100; 10 times 0.10 or 0.1 is 1.0.0803

Remember I move the decimal place over once because of that number.0816

It is 1.0 which is the same thing as 1.0820

My sales tax is going to be 1; let me move this over.0826

Give my dollar sign some room; my sales tax is going to be 1 dollar.0834

That is how much I have to pay in sales tax0838

for my shirt that costs 10 dollars if the tax rate is 10 percent.0840

The next example, we are going to buy a CD that costs 14 dollars.0850

It is not on sale even though that is better on sale.0855

It has 10 percent sales tax; let's see, sales tax.0860

What are we looking for?--total amount that we are going to end up paying.0874

Before we figure out the total amount, we need to know how much we are going to pay for sales tax.0878

The total due or the cost is going to be 14 dollars.0887

Times it by the sales tax rate which is 10 percent.0893

Again change this to a decimal; this is 14; this is one, two.0900

That is 0.10 or 0.1; 0.10, you can just drop the 0 if you want.0907

0; 0; 1 times 4 is 4; 1 times 1 is 1.0920

Put 0s in those spaces; add them; 0 plus 1 is 1.0928

0 plus 4 is 4; 0 plus 0 is 0; 140.0933

How many numbers do I have behind decimal points? I have two.0938

From here, I am going to go one, two.0943

It is going to be 1.40; that is money.0947

A dollar forty is how much I have to pay in addition to my 14 dollars I have to pay for the CD.0959

Total due, total is going to be the 14 dollars plus the dollar forty.0969

14 is the same thing as 14.00; plus 1.40.0982

When you add numbers with decimal points, you have to make sure0991

the decimal points are lined up, the two are lined up like this.0997

All the rest of the numbers are aligned also.1002

This is 0; this is 4; bring down the decimal point.1006

4 plus 1 is 5; 1; bring it down.1012

How much am I paying?--15 dollars and 40 cents.1016

That is how much I have to pay for a 14 dollar CD if I have to pay for sales tax.1025

That is it for this lesson; thank you for watching