9. $$\frac{2b(m+n)}{6bc(m+n)} =$$

$$\frac{2b(m+n)}{6bc(m+n)} = \frac{2}{6} \cdot \frac{b}{b} \cdot \frac{(m+n)}{(m+n)} \cdot \frac{1}{c} = \frac{1}{3} \cdot 1 \cdot 1 \cdot \frac{1}{c} = \frac{1}{3c}$$

Ответ: $$\frac{1}{3c}$$