б) $$\frac{63a^3b}{c} : (18a^2b) = \frac{63a^3b}{c} \cdot \frac{1}{18a^2b} = \frac{63}{18} \cdot \frac{a^3}{a^2} \cdot \frac{b}{b} \cdot \frac{1}{c} = \frac{7}{2} \cdot a \cdot 1 \cdot \frac{1}{c} = \frac{7a}{2c}$$
Ответ: $$\frac{7a}{2c}$$