б) 3/8 c³a²⋅(-2/3 c²d²)³;

б) $$
\frac{3}{8}c^3a^2 \cdot (-\frac{2}{3}c^2d^2)^3 = \frac{3}{8}c^3a^2 \cdot (-\frac{8}{27}c^6d^6) = \frac{3}{8} \cdot (-\frac{8}{27}) \cdot c^3 \cdot c^6 \cdot a^2 \cdot d^6 = -\frac{1}{9}a^2c^9d^6 $$

Ответ: $$\-\frac{1}{9}a^2c^9d^6$$