Упростите 5 * (х-2) - 6 * (х+3) - 3 * (2х - 9)
(5х-10)-(6х+12)-(6х-27)= 5х-10-6х-12-6х+27= -7х-5
5x - 10 - (6x + 18) - (6x - 27) = 5x - 10 - 6x - 18 - 6x + 27 = -7x -1
вот, кажется так.