inequalities gmatprep

[demoskopico]

If w + x < 0, is w – y > 0?

(1) x + y < 0
(2) y < x < w

OA is B.

My answer is D:

let's have a system:

w+x<0
w-y>0

this means that w+x<0 and -w+y<0. thus, adding up we would have: x+y<0, which is the first condition. where is my mistake? thanks.

[kevin]

You have shown that the answer could be yes, but this does not prove that the answer is yes.

All cats have four legs. Since Luigi has four legs, Luigi must be a cat?