3)13・0,625:号+[(1):2,1=

Выполним вычисления:

$$ 1\frac{5}{7} \cdot 0.625 : \frac{2}{7} + [(1\frac{1}{2})^3 - 3\frac{3}{4}] : 2.1 = $$

$$ = \frac{12}{7} \cdot 0.625 : \frac{2}{7} + [(\frac{3}{2})^3 - \frac{15}{4}] : 2.1 = $$

$$ = \frac{12}{7} \cdot \frac{5}{8} : \frac{2}{7} + [\frac{27}{8} - \frac{15}{4}] : 2.1 = $$

$$ = \frac{12}{7} \cdot \frac{5}{8} : \frac{2}{7} + [\frac{27}{8} - \frac{30}{8}] : 2.1 = $$

$$ = \frac{12}{7} \cdot \frac{5}{8} : \frac{2}{7} + [-\frac{3}{8}] : 2.1 = $$

$$ = \frac{60}{56} \cdot \frac{7}{2} + [-\frac{3}{8}] : \frac{21}{10} = $$

$$ = \frac{15}{14} \cdot \frac{7}{2} + [-\frac{3}{8}] \cdot \frac{10}{21} = $$

$$ = \frac{15}{2} \cdot \frac{1}{2} + [-\frac{1}{4} \cdot \frac{5}{7}] = $$

$$ = \frac{15}{4} - \frac{5}{28} = $$

$$ = \frac{15 \cdot 7}{4 \cdot 7} - \frac{5}{28} = $$

$$ = \frac{105}{28} - \frac{5}{28} = $$

$$ = \frac{100}{28} = $$

$$ = \frac{25}{7} = $$

$$ = 3\frac{4}{7} $$

Ответ: $$ 3\frac{4}{7} $$