\frac{5}{8}c^2d \cdot \frac{4}{5}cd^3

2. $$\frac{5}{8}c^2d \cdot \frac{4}{5}cd^3 = \frac{5 \cdot 4}{8 \cdot 5} \cdot (c^2 \cdot c) \cdot (d \cdot d^3) = \frac{20}{40} c^3d^4 = \frac{1}{2} c^3d^4$$

Ответ: $$\frac{1}{2} c^3d^4$$