в) n + \frac{5}{14}n = \frac{1}{7};

в) Решим уравнение:

$$n + \frac{5}{14}n = \frac{1}{7}$$

$$\frac{14}{14}n + \frac{5}{14}n = \frac{1}{7}$$

$$\frac{19}{14}n = \frac{1}{7}$$

$$n = \frac{1}{7} : \frac{19}{14}$$

$$n = \frac{1}{7} \cdot \frac{14}{19}$$

$$n = \frac{1}{1} \cdot \frac{2}{19}$$

$$n = \frac{2}{19}$$

Ответ: $$\frac{2}{19}$$