\[x - 3;\ \ \sqrt{5x};\ \ \ x + 4\]
\[\frac{\sqrt{5x}}{x - 3} = \frac{x + 4}{\sqrt{5x}}\]
\[\frac{(x + 4)(x - 3) - 5x}{\sqrt{5x}(x - 3)} = 0\ \ \ \ \ \ \ \ \]
\[x > 0;\ \ x \neq 3\]
\[(x + 4)(x - 3) - 5x = 0\]
\[x^{2} - 3x + 4x - 12 - 5x = 0\]
\[x^{2} - 4x - 12 = 0\]
\[x_{1} = - 2\ (не\ подходит);\ \ x_{2} = 6\]
\[Ответ:6.\]