Решите уравнение: (7a-1) * (a+5) = (3+7a) * (a+3)

(7 * a - 1) * (a + 5) = (3 + 7 * a) * (a + 3); 7 * a^2 + 5 * 7 * a - 1 * a - 5 * 1 = 3 * a + 3 * 3 + 7 * a * a + 3 * 7 * a; Вычислим а. 7 * a^2 + 35 * a - a - 5 = 3 * a + 9 + 7 * a^2 + 21 * a; 7 * a^2 + 34 * a - 5 = 7 * a^2 + 24 * a + 9; 7 * a^2 + 34 * a - 5 - 7 * a^2 - 24 * a - 9 = 0; 34 * a - 24 * a - 5 - 9 = 0; 10 * a - 14 = 0; 10 * a = 14; a = 14/10; a = 7/5.