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## Official Guide Explanation:Data Sufficiency #84

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.

Question: 84
Page: 159
Difficulty: 4 (Moderately Easy)
Category 1: Algebra > Linear Equations-Two Unk >
Category 2: Word Problems > Other >

Explanation: We're looking for the value of the expression 25p + 30n, where p is the weight of one photograph and n is the weight of one negative.

Statement (1) gives us one equation with the variables p and n (p = 3n), but no actual weight amount, so it is insufficient. Statement (2) offers another equation with the variables p and n (p + 2n = (1/3)) but nothing we can directly translate into the value of 25p + 30n.

Taken together, the statements are sufficient. We have two variables and two distinct linear equations. With those, we can find the values of p and n and plug them into the initial expression. Choice (C) is correct.

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