78-(15*Х/9-5)*7=156/2
78 - (15х/9 - 5)*7 = 78 78 - 105х/9 + 35 = 78 113 - 105х/9 = 78 - 105х : 9 = -113 + 78 - 105х = 9 (-113 + 78) - 105х = -1017 + 702 - 105х = - 315 х = 3