a) (x - 5)(x + 2) - (x + 1)(x - 6) = 8
x2 + 2x - 5x - 10 - (x2 - 6x + x - 6) = 8
x2 - 3x - 10 - x2 + 5x + 6 = 8
2x - 4 = 8
2x = 12
x = 6
Ответ: x = 6
б) $$\frac{7x+4}{10} - \frac{8x+6}{5} = 1$$
Домножаем обе части уравнения на 10:
$$(7x + 4) - 2(8x + 6) = 10$$
$$7x + 4 - 16x - 12 = 10$$
$$-9x - 8 = 10$$
$$-9x = 18$$
$$x = -2$$
Ответ: x = -2