You substitute each number for the one from the other equation.
-6x+-6x=6
-12x= 6
Divide both sides by -12.
x= -.5
Now, plug that in for y.
You can use any equation.
-6(-.5) +6y= 6
3+6y= 6
Subtract 3 on both sides.
6y= 3
y= 0.5.
(-0.5,0.5)
I hope this helps!
~kaikers