Official Guide Explanation:
Problem Solving #44

 

 

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: 44
Page: 67
Difficulty: 5 (Moderate)
Category 1: Geometry > Triangles > other
Category 2: Geometry > Triangles > Multiple figures

Explanation: It's tempting to treat this diagram as two separate triangles, but it's much simpler to think of it as one, with angles x, 70, and (37 + z). Since a triangle contains a total of 180 degrees, we can say that 180 = x + 70 + (37 + z), or 180 = 107 + x + z. To solve for x: x = 180 - 107 - z = 73 - z, choice (E).

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