Выполните вычитание: 20/(a^2+4a)-5/a.

\[\frac{20}{a^{2} + 4a} - \frac{5}{a} = \frac{20}{a(a + 4)} - \frac{5^{\backslash a + 4}}{a} =\]

\[= \frac{20 - 5a - 20}{a(a + 4)} = - \frac{5a}{a(a + 4)} =\]

\[= - \frac{5}{a + 4}.\]