Решение:

1. а) $$\frac{14p^4}{q^6} \cdot \frac{q^3}{56p^4} = \frac{14p^4q^3}{56p^4q^6} = \frac{14 \cdot p^4 \cdot q^3}{14 \cdot 4 \cdot p^4 \cdot q^3 \cdot q^3} = \frac{1}{4q^3}$$
2. б) $$45a^3b \cdot \frac{c^2}{30a^4b} = \frac{45a^3bc^2}{30a^4b} = \frac{15 \cdot 3 \cdot a^3 \cdot b \cdot c^2}{15 \cdot 2 \cdot a^3 \cdot a \cdot b} = \frac{3c^2}{2a}$$
3. в) $$\frac{3a-9}{a+2} : \frac{a^2-9}{a^2-4} = \frac{3a-9}{a+2} \cdot \frac{a^2-4}{a^2-9} = \frac{3(a-3)}{a+2} \cdot \frac{(a-2)(a+2)}{(a-3)(a+3)} = \frac{3(a-2)}{a+3}$$

Ответ:

1. а) $$\frac{1}{4q^3}$$
2. б) $$\frac{3c^2}{2a}$$
3. в) $$\frac{3(a-2)}{a+3}$$