Official Guide Explanation:
Data Sufficiency #44

Background

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Solution and Metadata

Question: 44
Page: 156
Difficulty: 5 (Moderate)
Category 1: Arithmetic > Properties of Integers > Other
Category 2: Algebra > Linear Equations-Two Unk >

Explanation: Statement (1) is insufficient: it provides two equations--x - y = 3 and x + y = 9--but it isn't clear which digit is which. The values that fulfill those equations are x = 6 and y = 3, so Q could be 36 or 63. Statement (2) is insufficient: Q could be any number between 10 and 50.

Taken together, the statements are sufficient: if Q is 36 or 63 and Q < 50, Q must be equal to 36. Choice (C) is correct.

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