б) (a-1)² 5a-5 2b: 4b

б) $$ \frac{(a-1)^2}{2b} : \frac{5a-5}{4b} = \frac{(a-1)^2}{2b} \cdot \frac{4b}{5a-5} = \frac{4b(a-1)^2}{2b(5(a-1))} = \frac{2(a-1)}{5} $$

Ответ: $$ \frac{2(a-1)}{5} $$