5. Решим уравнение:
$$x = 8\frac{9}{10} - 4\frac{5}{6}$$
$$x = 8 - 4 + \frac{9}{10} - \frac{5}{6}$$
$$x = 4 + \frac{9 \times 3}{10 \times 3} - \frac{5 \times 5}{6 \times 5}$$
$$x = 4 + \frac{27}{30} - \frac{25}{30}$$
$$x = 4 + \frac{2}{30}$$
$$x = 4\frac{1}{15}$$
$$x = 10\frac{7}{6} + 6\frac{3}{11}$$
$$x = 10 + 6 + \frac{7}{6} + \frac{3}{11}$$
$$x = 16 + \frac{7 \times 11}{6 \times 11} + \frac{3 \times 6}{11 \times 6}$$
$$x = 16 + \frac{77}{66} + \frac{18}{66}$$
$$x = 16 + \frac{95}{66}$$
$$x = 16 + 1\frac{29}{66}$$
$$x = 17\frac{29}{66}$$
Ответ: a) $$x = 4\frac{1}{15}$$; б) $$x = 17\frac{29}{66}$$