Max@Math Revolution wrote:Is x < y?
1) x - y < -4
2) -2x > -2y
Nice question.
Target question: Is x < y?
Statement 1: x - y < -4
Add y to both sides to get: x < y - 4
IMPORTANT: we know that y - 4 < y
So, we can combine
y - 4 < y with x <
y - 4 to get: x <
y - 4 < y
From this we can conclude that
x < y
Since we can answer the
target question with certainty, statement 1 is SUFFICIENT
Statement 2: -2x > -2y
Divide both sides of the inequality by -2 to get:
x < y [aside: when we divide both sides of an inequality by a negative value, we must switch the direction of the inequality]
Since we can answer the
target question with certainty, statement 2 is SUFFICIENT
Answer =
D
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