elimitation method
basically eliminate one of the terms completely
we see that there is a -2x and a 2x in the 2 equations
so just add them together
2x-2x+4y+y=18-8
5y=10
divide both sides by 5
y=2
subsitute
-2x+2=-8
subtract 2 form boht sides
-2x=-10
divide both sides by 2
-x=5
multiply -1
x=5
y=2
x=5