Data Sufficiency

If x ≠ -y, is (x - y)/(x + y) > 0?

1) x > 0
2) y < 0

NOTE: If we have a feeling that the statements might not be sufficient, we can start TESTING VALUES.

Target question: Is (x - y)/(x + y) > 0?

Statement 1: x > 0
There are several values of x and y that satisfy this condition. Here are two:
Case a: x = 2 and y = -1, in which case (x - y)/(x + y) is GREATER THAN 0
Case b: x = 2 and y = -3, in which case (x - y)/(x + y) is LESS THAN 0
Since we cannot answer the target question with certainty, statement 1 is NOT SUFFICIENT

Statement 2: y < 0
There are several values of x and y that satisfy this condition. Here are two:
Case a: x = 2 and y = -1, in which case (x - y)/(x + y) is GREATER THAN 0
Case b: x = 2 and y = -3, in which case (x - y)/(x + y) is LESS THAN 0
Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT

Statements 1 and 2 combined
There are several values of x and y that satisfy BOTH conditions. Here are two:
Case a: x = 2 and y = -1, in which case (x - y)/(x + y) is GREATER THAN 0
Case b: x = 2 and y = -3, in which case (x - y)/(x + y) is LESS THAN 0
Since we cannot answer the target question with certainty, the combined statements are NOT SUFFICIENT

Answer = E

Cheers,
Brent