Use the substitution method to solve the system of equations.
x+y=11
-x=-y-9

Like you said, we need to use substitution to solve for y.

Now that we've solved for y, we can plug in the number we got into one of the original equations. (You can choose either equation, but I will use the first one.)

Now we have the solution of this system.

step-by-step explanation:

i am not sure sorry : c

this is false ^.^ lol