6 3) 5m 2n 25k.

3) $$5m \cdot \frac{2}{11}n \cdot 2\frac{5}{14}k = 5m \cdot \frac{2}{11}n \cdot \frac{2 \cdot 14 + 5}{14}k = 5m \cdot \frac{2}{11}n \cdot \frac{28 + 5}{14}k = 5m \cdot \frac{2}{11}n \cdot \frac{33}{14}k = \frac{5 \cdot 2 \cdot 33}{11 \cdot 14} mnk = \frac{330}{154} mnk = \frac{165}{77} mnk = \frac{15}{7} mnk = 2\frac{1}{7} mnk$$

Ответ: $$2\frac{1}{7}mnk$$