a) $$\frac{5}{11} - x = \frac{5}{33}$$
$$x = \frac{5}{11} - \frac{5}{33} = \frac{5 \cdot 3}{11 \cdot 3} - \frac{5}{33} = \frac{15}{33} - \frac{5}{33} = \frac{15-5}{33} = \frac{10}{33}$$
Ответ: $$\frac{10}{33}$$
б) $$6,28n - 2,8n = 36,54$$
$$(6,28 - 2,8)n = 36,54$$
$$3,48n = 36,54$$
$$n = \frac{36,54}{3,48} = 10,5$$
Ответ: 10,5