Check it out:

9 - 3x + 3x = 5x + 3x + 6  ditch the 6...  9 - 6 = 8x +6 -6  ditch the 8...  3 / 8 = 8x / 8  which gives  3/8 = x

Check it by sticking it back into both sides:

9 - 3x = 5x + 6  substitute  9 - 3(3/8) = 5(3/8) + 6  which gives  72/8 - 9/8 = 15/8 + 48/8  which gives  63/8 = 63/8


YOUR TURN:

Solve          2x + 9 = 6x - 3          *And check it!