Official Guide Explanation:
Problem Solving #100




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Solution and Metadata

Question: 100
Page: 74
Difficulty: 5 (Moderate)
Category 1: Arithmetic > Percents > other
Category 2: Arithmetic > Percents > Percent Change
Category 3: Word Problems > Discount >

Explanation: This is a great question to use an actual number instead of a variable. Say that Carlos earned $100 last year. If he saved 10% of that, he saved 10%($100) = $10. If he earned 5 percent more this year, that's $100 + 5%($100) = $100 + $5 = $105. 12 percent of that will take a little work, but it works out to $12.60. The question is asking, then, what percent $12.60 is of $10. Doing the math isn't necessary: since $10 is such a simple number to work with, it's evident that the correct answer is choice (C), 126%.

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