Решение примеров:

1)

$$ (9,9-5,52:0,69+8,1)-(5-0,125):(3,7+0,05)) = $$ $$ (9,9 - 8 + 8,1) - (4,875 : 3,75) = $$ $$ 10 - 1,3 = 8,7 $$

2)

a)

$$ \frac{4}{9} \cdot \frac{63}{64} : \frac{7}{4} = $$ $$ \frac{4}{9} \cdot \frac{63}{64} \cdot \frac{4}{7} = $$ $$ \frac{4 \cdot 63 \cdot 4}{9 \cdot 64 \cdot 7} = \frac{1008}{4032} = \frac{1}{4} $$

б)

$$ (\frac{1}{2}):\frac{5}{6} \cdot \frac{7}{15} = $$ $$ \frac{1}{2} \cdot \frac{6}{5} \cdot \frac{7}{15} = $$ $$ \frac{1 \cdot 6 \cdot 7}{2 \cdot 5 \cdot 15} = \frac{42}{150} = \frac{7}{25} $$

в)

$$ (1-\frac{1}{3}) : (\frac{1}{3} - \frac{1}{4}) = $$ $$ (\frac{3}{3} - \frac{1}{3}) : (\frac{4}{12} - \frac{3}{12}) = $$ $$ \frac{2}{3} : \frac{1}{12} = \frac{2}{3} \cdot \frac{12}{1} = \frac{2 \cdot 12}{3 \cdot 1} = \frac{24}{3} = 8 $$

3)

a)

$$ (\frac{4}{30} + \frac{1}{2} + \frac{4}{15}) : (\frac{49}{50} - \frac{14}{25} - \frac{2}{5}) = $$ $$ (\frac{4}{30} + \frac{15}{30} + \frac{8}{30}) : (\frac{49}{50} - \frac{28}{50} - \frac{20}{50}) = $$ $$ \frac{27}{30} : \frac{1}{50} = $$ $$ \frac{27}{30} \cdot \frac{50}{1} = \frac{27 \cdot 50}{30 \cdot 1} = \frac{1350}{30} = 45 $$

б)

$$ 39: (\frac{3}{8} + \frac{1}{6}) + (\frac{3}{10})^{2} : (\frac{4}{3} - \frac{7}{18}) = $$ $$ 39: (\frac{9}{24} + \frac{4}{24}) + \frac{9}{100} : (\frac{24}{18} - \frac{7}{18}) = $$ $$ 39: \frac{13}{24} + \frac{9}{100} : \frac{17}{18} = $$ $$ 39 \cdot \frac{24}{13} + \frac{9}{100} \cdot \frac{18}{17} = $$ $$ \frac{39 \cdot 24}{13} + \frac{9 \cdot 18}{100 \cdot 17} = $$ $$ 3 \cdot 24 + \frac{162}{1700} = 72 + \frac{81}{850} = 72 \frac{81}{850} $$

Ответы:

1) 8,7

2) a) 1/4, б) 7/25, в) 8

3) а) 45, б) $$ 72 \frac{81}{850} $$