Multiplying so both equations have the same leading coefficient
In this case the coefficient of x of the first
x + 3y = -7
is 1
and for the second
-x + 2y = -8
the coefficient is -1
We multiply the second by -1 both sides, so the coefficient is +1
-x + 2y = -8
-1 (-x + 2y ) = -1( -8)
x -2y = 8
Now we have
x + 3y = -7
x -2y = 8
Subtracting the second equation from the first
x + 3y = -7
x -2y = 8
Substracting them:
