6-(2x-9) = (18+2x)-3*(x-3)
6-2x+9 = (18+2x)-3*(x-3)
6-2x+9 = 18+2x-3x+3*3
15 - 2x = 18+2x-3x+3*3
15 - 2x = 27 - x
-2x = -x + 12
-x = 12
x = -12
Получим ответ: x = -12