б) (a-2)²3a-6 b+5 2b+10

б) $$ \frac{(a-2)^2}{b+5} : \frac{3a-6}{2b+10} = \frac{(a-2)^2}{b+5} \cdot \frac{2b+10}{3a-6} = \frac{(a-2)^2}{b+5} \cdot \frac{2(b+5)}{3(a-2)} = \frac{2(a-2)^2(b+5)}{3(b+5)(a-2)} = \frac{2(a-2)}{3} $$

Ответ: $$ \frac{2(a-2)}{3} $$