3(x - 2y) - 4(2x + 3y) for x = -1 and y = 3
3 [ -1 - 2(3) ] - 4 [ 2(-1) + 3(3) ] =
3 [ - 1 - 6 ] - 4 [ -2 + 9 ] =
3 [ - 7 ] - 4 [ 7 ] =
-21 - 28 =
-49
