Решите уравнение: 7x - 5(2x + 1) = 5x + 15.

Ответ:

7x - 10x - 5 = 5x + 15 => -3x - 5 = 5x + 15 => -3x - 5x = 15 + 5 => -8x = 20 => x = -2.5.