Вычислите: б) $$\frac{8}{21} \cdot \frac{1}{4} + \frac{2}{3} : \frac{7}{6}$$

$$\frac{8}{21} \cdot \frac{1}{4} + \frac{2}{3} : \frac{7}{6} = \frac{8}{21} \cdot \frac{1}{4} + \frac{2}{3} \cdot \frac{6}{7} = \frac{8}{84} + \frac{12}{21} = \frac{2}{21} + \frac{12}{21} = \frac{14}{21} = \frac{2}{3}$$ Ответ: $$\frac{2}{3}$$