485 1) 8a2b 36c³ 9c 5a3b

1) $$ \frac{8a^2b}{9c} : \frac{36c^3}{5a^3b} = \frac{8a^2b}{9c} \cdot \frac{5a^3b}{36c^3} = \frac{8a^2b \cdot 5a^3b}{9c \cdot 36c^3} = \frac{40a^5b^2}{324c^4} = \frac{10a^5b^2}{81c^4} $$

Ответ: $$ \frac{10a^5b^2}{81c^4} $$