so, it says x + y = -2
we just plug in the numbers so,
2 + - 4 = -2
This equation is true and can also be written as
2 - 4 = -2
It also then says that 2x - y = 8
Again, you just plug in the numbers
2 * 2 - (-4) = 8
This equation is true and can also be writen as,
2*2 + 4 = 8
