EQUATION #1) 2x=y-10
EQUATION #2) x+7=y
On both equations, move the equation around so that both variables are on the same side of the equal sign.
1) 2x-y=-10
2) x-y=-7
Subtract equations together.
1) 2x-y=-10
2) x-y=-7
x=-3
Plug x into equation number 2.
1) x+7=y
1) (2) + 7 = y
9=y
y=9
~Hope I helped!~
