Решите уравнение: (3x + 1)(5x − 1) = (5x + 2)(3x − 4) − 7x.

\[(3x + 1)(5x - 1) = (5x + 2)(3x - 4) - 7x\]

\[15x^{2} + 5x - 3x - 1 = 15x^{2} + 6x - 20x - 8 - 7x\]

\[2x + 21x = - 8 + 1\]

\[23x = - 7\]

\[x = - \frac{7}{23}.\]