4. Решите уравнение:
a) $$(x - \frac{8}{9}) + 3\frac{7}{9} = 4\frac{4}{9}$$
$$x - \frac{8}{9} = 4\frac{4}{9} - 3\frac{7}{9}$$
$$x - \frac{8}{9} = \frac{40}{9} - \frac{34}{9}$$
$$x - \frac{8}{9} = \frac{10}{9}$$
$$x = \frac{10}{9} + \frac{8}{9}$$
$$x = \frac{18}{9}$$
$$x = 2$$
б) $$\left(3\frac{9}{13} + x\right) - 4 = 1\frac{7}{13}$$
$$3\frac{9}{13} + x = 1\frac{7}{13} + 4$$
$$3\frac{9}{13} + x = 5\frac{7}{13}$$
$$x = 5\frac{7}{13} - 3\frac{9}{13}$$
$$x = 4\frac{20}{13} - 3\frac{9}{13}$$
$$x = 1\frac{11}{13}$$
Ответ: $$x = 2$$, $$x = 1\frac{11}{13}$$