93. Выполните вычитание дробей: a) $$\frac{a^2 + 3a}{ab-5b+8a-40} - \frac{a}{b+8}$$

a) $$\frac{a^2 + 3a}{ab-5b+8a-40} - \frac{a}{b+8} = \frac{a(a+3)}{b(a-5) + 8(a-5)} - \frac{a}{b+8} = \frac{a(a+3)}{(b+8)(a-5)} - \frac{a}{b+8} = \frac{a(a+3) - a(a-5)}{(b+8)(a-5)} = \frac{a^2 + 3a - a^2 + 5a}{(b+8)(a-5)} = \frac{8a}{(b+8)(a-5)}$$