Выполните вычитание 36/(a^2+3a)-12/a.

\[\frac{36}{a^{2} + 3a} - \frac{12}{a} = \frac{36}{a(a + 3)} - \frac{12^{\backslash a + 3}}{a} =\]

\[= \frac{36 - 12a - 36}{a(a + 3)} = - \frac{12a}{a(a + 3)} = - \frac{12}{a + 3}\]