Решите уравнение: 5x(x-4)-x(3+5x)=4.

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

\[5x^{2} - 20x - 3x - 5x^{2} = 4\]

\[- 23x = 4\]

\[x = - \frac{4}{23}\]

\[Ответ:\ x = - \frac{4}{23}.\]