The first equation goes as follows:

-(x+y)=x-y
-x-y=x-y
-y-y=2x
2x=0
x=0 (sufficient)

And the second equation:
x=2-y

depends on value of Y (insufficient)

BlindVision wrote:What is the value of x?

1) -(x + y) = x - y

2) x + y = 2

OA = A

I haven't the slightest idea how the answer came to be?

What is X ? and there are two variables, X and Y.

This smells C-trap all over the question. But let's start with the easiest statement, Statement II.

We don't know y, so we can not solve for X. INSUF

Now we are left with A, C and E ( your chance of guessing this question went up from 20% to 33%)

Let's work with statement I)

-(x + y) = x - y

-x-y=x-y ( cancel -y on the both side )

-x=x ; 2x=0 and x=0 we know what X is!!

Remember we dont need to carry on the calculation, so dark red part is not neccesary in GMAT. Once you figure out that you can solve the problem...STOP!

I got it because of you guys! Thank you so much!