2) $$\frac{4,8}{1\frac{7}{9}} = (1,2b) : 6\frac{2}{3}$$;

Решим уравнение:

$$\frac{4,8}{1\frac{7}{9}} = (1,2b) : 6\frac{2}{3}$$.

$$\frac{4,8}{\frac{16}{9}} = (1,2b) : \frac{20}{3}$$.

$$\frac{48}{10} * \frac{9}{16} = (1,2b) * \frac{3}{20}$$.

$$\frac{3}{10} * \frac{9}{1} = (1,2b) * \frac{3}{20}$$.

$$\frac{27}{10} = (1,2b) * \frac{3}{20}$$.

$$1,2b = \frac{27 * 20}{10 * 3}$$.

$$1,2b = \frac{9 * 2}{1 * 1}$$.

$$1,2b = 18$$.

$$b = \frac{18}{1,2} = \frac{180}{12} = 15$$.

Ответ: $$b = 15$$.