Official Guide Explanation:
Data Sufficiency #80

Background

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Solution and Metadata

Question: 80
Page: 158
Difficulty: 5 (Moderate)
Category 1: Algebra > Linear Equations-Two Unk >

Explanation: Statement (1) is insufficient: there are several possible values for x and y, so there are several possible results for xy. Statement (2) is also insufficient, for the same reason.

Taken together, the statements are sufficient. Each statement has one linear equation with two variables; put them together, you have two variables and two distinct linear equations. There's no need to figure out the exact values of x and y; recognize that you can, and select choice (C).

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