$\frac{3a + 2}{5a + 7}$ = $\frac{3a - 1}{5a - 1}$ Đkxđ: a $\neq$ -$\frac{7}{5}$; a $\neq$ $\frac{1}{5}$
(3a + 2)(5a - 1) = (5a + 7)(3a - 1)
15a² - 3a + 10a - 2 = 15a² - 5a + 21a - 7
15a² - 3a + 10a - 2 - 15a² + 5a - 21a + 7 = 0
-9a + 5 = 0
-9a = -5
a = $\frac{5}{9}$ (t/m)
Vậy a = $\frac{5}{9}$