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## Official Guide Explanation:

Data Sufficiency #26

**Background**

This is just one of hundreds of free explanations I've created to the quantitative questions in The Official Guide for GMAT Quantitative Review (2nd ed.). Click the links on the question number, difficulty level, and categories to find explanations for other problems.

These are the same explanations that are featured in my "Guides to the Official Guide" PDF booklets. However, because of the limitations of HTML and cross-browser compatibility, some mathematical concepts, such as fractions and roots, do not display as clearly online.

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**Solution and Metadata**

**Question****: 26**

Page: 155

Difficulty: **4** (Moderately Easy)

Category 1: Word Problems > Other >

Category 2: Algebra > Linear Equations-One Unk >

**Explanation:** Statement (1) is sufficient, as it provides two equations with a total of two variables. The number of papers sold yesterday is 100, so y = 100. If that's 10 fewer than twice the number sold today, 2t - 10 = y. Substituting in the value of y, you can solve for the value of t, the number of papers sold today.

Statement (2) is insufficient: it also has two variables, but only offers one equation. Choice (A) is correct.

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