Algebra Honors help...

For the following system, if you isolated y in the first equation to use the Substitution Method, what expression would you substitute into the second equation?

2x + y = 8
-x - y = -5

8 - 2x

8 + 2x

-8 - 2x

-8 + 2x

EDIT:

this is my second time asking, so please?

If you isolated y in the first equation you would end up getting:

y=8-2x

Basically subtract the 2x on both sides and you get y.

I'm guessing what you listed after the first two equations are choices. So A is my answer.

8-2x
When you solve for "Y" it equals 8-2x so because we know both y's are the same thing you can plug that in and find X

8 - 2x