You can put this solution on YOUR website! To find out, you can either solve the system, or you can merely plug (-3,5) into both equations to see if it makes them true statements...so for
-x + 2y = 13
-x - y = -2
Turns out that (-3,5) does make both true...for example
-(-3) + 2(5) = 3 + 10 = 13