## Algebra 1: Common Core (15th Edition)

Published by Prentice Hall

# Chapter 2 - Solving Equations - 2-1 Solving One-Step Equations - Practice and Problem-Solving Exercises - Page 85: 33

#### Answer

$r=-1/2$

#### Work Step by Step

In order to solve this algebraic expression, we must isolate the variable. A variable is the letter in the problem (for instance, in the equation 2x=10, x is the variable). Because multiplication and division are inverse operations (they cancel each other out), we know we must divide when a number is being multiplied by the variable and multiply when the variable is being divided by a number. In the equation $7r=-7/2$, we must get rid of the 7, which the variable is being multiplied by, in order to solve. Thus, we divide both sides by 7 to find that $r=-1/2$. We plug -1/2 in for r and confirm that our answer is, indeed, correct.

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