Since both equations have 3y, we will substitute 3y.
2x-3y = 20 eq 1
rearrange
2x - 20 = 3y
sub the value of 3y into eq2
11x + (2x-20) = -1
11x + 2x - 20 = -1
13x = 19
x =19/13
sub value of x into any equation
2(19/13) - 3y =20
38/13 - 20 = 3y
-222/13 = 3y
y = -74/13
