(2х+3)+(3х+4)+(5х+5)=12-7х
(2х + 3) + (3х + 4) + (5х + 5) = 12 - 7х 2х + 3 + 3х + 4 + 5х + 5 = 12 - 7х 10 х + 12 = 12 - 7х 17х = 0 х = 0 Ответ : 0