Big Ideas Math: Modeling Real Life, Grade 7
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1. Solving Equations Using Addition or Subtraction
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Exercise 5 Page 129

Use the Addition Property of Equality to eliminate the subtraction.

c=8

Practice makes perfect
To solve the equation, we have to isolate c on one side. Using the Addition Property of Equality, we will add 12 to both sides of the equation. This will eliminate the subtraction and isolate c.
c - 12 = - 4
c - 12 + 12 = - 4 + 12
c = 8
To check that this solution is correct, let's substitute c=8 into the original equation and simplify.
c - 12 = - 4
8 - 12? =- 4
- 4 = - 4 âś“
Since the left-hand side and right-hand side are equal, c=8 is the correct solution.