Sign In | Subscribe
Start learning today, and be successful in your academic & professional career. Start Today!
Loading video...
This is a quick preview of the lesson. For full access, please Log In or Sign up.
For more information, please see full course syllabus of Pre Algebra
  • Discussion

  • Study Guides

  • Practice Questions

  • Download Lecture Slides

  • Table of Contents

  • Related Books

Bookmark and Share
Lecture Comments (4)

0 answers

Post by saimon biniam on August 5 at 07:13:05 PM

27=-65+y is not 91 it's 92, you should to double check it please.don't make us confuse!

0 answers

Post by Terrance Goins on July 18, 2015

27=-65+y the answer is 92 not 91 why isn't this work double checked we
are paying customers?

0 answers

Post by GLENN MENSAH on March 24, 2014

this helps she is very very smart

0 answers

Post by brandon smith on April 21, 2013

how do you know how to set up all these word problems? I understand that the unknown in the word problem is the variable, but I don't understand how your ordering the rest of the problem into the equation.

thank you

Brandon

Solving Subtraction Equations

  • Inverse operations are those that undo each other. Addition and subtraction are inverse operations. Multiplication and Division are inverse operations.
  • You can use addition to solve a subtraction equation. Since addition is the inverse operation to subtraction, it will undo the subtraction and isolate the variable; for example, x − 8 = 11. If you add 8 to both sides, it will cancel the minus 8 leaving you with zero and the x all alone. Then you will see that x = 19.
  • The Subtraction Property of Equality says that if you subtract the same number from each side of an equation, the two sides remain equal.

Solving Subtraction Equations

Solve for m.
57 − m = 3
  • 57 = 3 + m
54 = m
Solve for x.
x − 65 = 35
  • x = 35 + 65
x = 100
Solve for a.
a − 3.2 = 47.5
  • a = 47.5 + 3.2
a = 50.7
Solve for b.
− 7.3 + b = 8.1
  • b = 8.1 + 7.3
b = 15.4
Solve for c.
− 54 − c = 60
  • − 54 = 60 + c
− 114 = c
Solve for y.
27 = − 65 + y
  • 27 + 65 = y
91 = y
Richard uses his allowance to buy a jacket that costs $ 18.75. He now has $ 54.32 left of his allowance. How much money did richard have before he bought the jacket?
  • Let m = how much money Richard had before.
  • m − $ 18.75 = $ 65.32
m = $ 84.07
Stephanie bought a set of headphones for $ 35.91 and resold it. Her profit was $ 15.46. How much did Stephanie resell the set for?
  • Let x = how much Stephanie resold the set for.
  • x − $ 15.46 = $ 35.91
x = $ 51.37
Michelle is walking back home in a straight line. After she walks 54 feet, she still has 78 feet to go. How far was Michelle from her house before she started walking?
  • Let d = how far Michelle was from her house before she started walking.
  • d − 54 = 78
  • d = 78 + 54
  • d = 132
132 feet
Sometimes, Albert drives to school, and sometimes, he walks. If he drives, he gets to school 7 minutes faster. It takes him 4 minutes to drive to school. How long does it take him to walk to school?
  • Let t = how long it takes him to walk to school.
  • t − 7 = 4
  • t = 11
11 minutes

*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.

Answer

Solving Subtraction Equations

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
  • What You'll Learn and Why 0:05
    • Topics Overview
  • Vocabulary 0:23
    • Addition Property of Equality: Arithmetic
    • Addition Property of Equality: Algebraic
    • Subtraction Property of Equality: Arithmetic
    • Subtraction Property of Equality: Algebraic
  • Solving an Equation by Adding 3:05
    • Example: b - 2 = 2
    • Example: 23 - j = 12
  • Solving an Equation by Adding 5:29
    • Example: a - 7.9 = 17.9
    • Example: -5.6 + x = 10.2
  • Solving an Equation by Writing an Equation 7:42
    • Example: Bank Withdrawal
  • Solving an Equation by Writing an Equation 9:21
    • Example: Temperature
  • Extra Example 1: Solving Subtraction Equations 11:50
  • Extra Example 2: Solving Subtraction Equations 12:46
  • Extra Example 3: Money 13:40
  • Extra Example 4: Selling Price 16:01