Решите систему 21m + 20n = 123 42m - 30n = 36

Система уравнений:

{ 21 * m + 20 * n = 123, 42 * m - 30 * n = 36;

{ 20 * n = 123 - 21 * m, 42 * m - 36 = 30 * n;

{ n = (123 - 21 * m) / 20, (42 * m - 36) / 30 = n;

Отсюда, (123 - 21 * m) / 20 = (42 * m - 36) / 30;

(123 - 21 * m) / 20 * 60 = (42 * m - 36) / 30 * 60;

3 * (123 - 21 * m) = 2 * (42 * m - 36);

369 - 63 * m = 84 * m - 72;

84 * m + 63 * m = 369 + 72;

147 * m = 441;

m = 441 / 147;

m = 3;

Тогда: n = (123 - 21 * m) / 20 = (123 - 21 * 3) / 20 = (123 - 63) / 20 = 60 / 20 = 3;

Ответ: m = 3 и n = 3.