2x + y = -1 and -x + y = -7
y = x - 7 from second equation, isolate y
2x + x - 7 = -1 plugin second equation into first
3x - 7 = -1 add the x together
3x = 6 add 7 to the other side to isolate x
x = 3 divide 6 by 3 to isolate x
y = 3 - 7 plugin x for the 3rd isolate y equation
y = -4 add
(3, -4)
-lekrj :) did you understand? hope you did