Решите номер 6 пожалуйста

4x + 3 = 2a - 1                             3x + 7 = a + 2
4x = 2a - 1 - 3                              3x = a + 2 - 7
4x = 2a - 4                                   3x = a - 5
x = 1/2a - 1                                  x = 1/3a - 5/3
$\frac{1}{2} a-1= \frac{1}{3}a - \frac{5}{3}\\\\ \frac{1}{2}a- \frac{1}{3}a=1-1 \frac{2}{3}\\\\ \frac{3}{6} a- \frac{2}{6} a=- \frac{2}{3}\\\\ \frac{1}{6}a=- \frac{2}{3}\\\\a=-4$