first for the first equation x = 2y +15 Substitute x in the second equation 2( 2y + 15) + 4 y = +18 4y + 30 + 4 y = -18 8y + 30 = -18 8y = -18 -30 8y = -48 y = -6
Substitute in first equation x -2(-6) = 15 x +12 = 15 x = 15 - 12 x = 3 so the solution is (3, -6)