Official Guide Explanation:
Data Sufficiency #94

Background

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Solution and Metadata

Question: 94
Page: 281
Difficulty: 6 (Moderately Difficult)
Category 1: Geometry > Coordinate Geometry > Slope
Category 2: Geometry > Coordinate Geometry > Other

Explanation: Given the equation of a line in standard form (as it is given to us in this question), the slope is m. That's what we need to answer the question.

Statement (1) is sufficient. Parallel lines have equal slopes. The line in (1) is also given in point - slope form, only the slope is (1 - m) and the y - intercept is b + 1 . We can ignore the intercept since we only care about the slope. Since the slopes of this line and the one in the question are the same, we can set them equal to each other:

m = 1 - m

2m = 1

m = (1/2)

Statement (2) is insufficient. To say that a line intersects another line tells you only one thing: They are not parallel. So, the only relevant information is that the line we care about passes through the point (2,7). If we knew another point as well, we could calculate the slope. However, with just one point, we can't. Choice (A) is correct.

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