\[a - \frac{a^{2} - 5a}{a + 1} \cdot \frac{1}{a - 5} = a - \frac{a(a - 5)}{a + 1} \cdot \frac{1}{a - 5} =\]
\[= a^{\backslash a + 1} - \frac{a}{a + 1} = \frac{a^{2} + a - a}{a + 1} =\]
\[= \frac{a^{2}}{a + 1}.\]