3x - y = 0
5x + 5 = 0
Solve for x:
5x + 5 = 0
5x = -5 [Subtract 5 from both sides]
x = -1 [Divide both sides by 5]
Plug x = -1 into the first equation and solve for y:
3x - y = 0
3(-1) - y = 0 [Plugged in -1 in place of x, since x = -1]
-3 - y = 0 [Add y to both sides]
-3 = y