Data Sufficiency

If x and y are integers and x > 0, is y > 0?
(1) 7x – 2y > 0
(2) -y < x

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.

I chose C, with the reasoning as follows:
(2) can be written as x+y>0, thus 7x+7y>0;
add (2) to (1), we get 5y>0, thus y>0

What's wrong with this reasoning? Can someone help me out? Thanks![/b]