14 - (5 х-6 1/7) = 6/7 * (5-12 х)

Найдем корни.

14 - (5 * х - 6 1/7) = 6/7 * (5 - 12 * х);

Раскроем скобки.

14 - 5 * x + 6 1/7 = 6/7 * 5 - 6/7 * 12 * x;

14 - 5 * x + 43/7 = 30/7 - 84/7 * x;

Умножим уравнение на 7.

14 * 7 - 5 * x * 7 + 43/7 * 7 = 30/7 * 7 - 84/7 * 7 * x;

70 + 28 - 35 * x + 43 = 30 - 84 * x;

98 - 35 * x + 43 = 30 - 84 * x;

141 - 35 * x = 30 - 84 * x;

-35 * x + 84 * x = 30 - 141;

84 * x - 35 * x = - 111;

x * (84 - 35) = - 111;

x * 49 = - 111;

49 * x = - 111;

x = - 111/49;

x = - 2 13/49.