Решите уравнение: 9 − 7(x + 3) = 5 − 4x.

\[9 - 7x - 21 = 5 - 4x\]

\[- 7x + 4x = 5 + 12\]

\[- 3x = 17\]

\[x = - \frac{17}{3}\]

\[x = - 5\frac{2}{3}.\]