3) 2md3=2d m2d2 m

3) $$ \frac{2md^3}{m^2d^2} = \frac{2 \cdot m \cdot d^2 \cdot d}{m \cdot m \cdot d^2} = \frac{2d}{m} $$

Ответ: $$\frac{2d}{m}$$