Verified answer

((6x/7)-4)*14-5*(21-3x)=-188

12x-56-105+15x=-188

27x-161=-188

27x=-27  |÷27

x=-1.

Ответ: x=-1.

12x - 56 - 105 + 15x = -188

12x + 15x = -188 + 56 + 105

27x = -27

x = (-27) / 27 = -1