Quote Originally Posted by rivdee View Post
Just for a more reasonable explanation, if you solve both in terms of y, you get:

y=3-3x
y=3+x

so 3-3x = 3+x, which balances to -3x = x (x can only be 0)

y = 3 - 3(0) = 3
y = 3 + (0) = 3
where you gettin y=3+x, second equation was x-5y=-15 which is y=(x+15)/5, which is y=x/5 + 3, just being nit picky, you get same answer.