Official Guide Explanation:
Problem Solving #99




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Solution and Metadata

Question: 99
Page: 74
Difficulty: 5 (Moderate)
Category 1: Algebra > Simplifying Algebraic Expressions >
Category 2: Algebra > Equations >

Explanation: You could try to rearrange the equation a + b = c to make it look like one of the five answer choices, but it's probably faster to assign values to each of the variables and test them in the answer choices. Say a = 2, b = 3, and c = 5. Those satisfy the initial equation. Check to see which of the answer choices is equal to 1 with those numbers:

(A) ((a - b)/(c)) = ((2 - 3)/5) = ((-1)/5)= - (1/5)

(B) ((a - c)/(b)) = ((2 - 5)/3) = ((-3)/3)= - 1

(C) ((b - c)/(a)) = ((3 - 5)/2) = ((-2)/2)= - 1

(D) ((b - a)/(c)) = ((3 - 2)/5) = (1/5)

(E) ((c - b)/(a)) = ((5 - 3)/2) = (2/2) = 2. That's it.

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