1) Найти значение выражения 1 - 3/7 * 4 1/5

Решения: 1) $1 - \frac{3}{7} \cdot 4\frac{1}{5} = 1 - \frac{3}{7} \cdot \frac{21}{5} = 1 - \frac{3 \cdot 21}{7 \cdot 5} = 1 - \frac{3 \cdot 3}{5} = 1 - \frac{9}{5} = 1 - 1\frac{4}{5} = -\frac{4}{5}$ 2) $\frac{72}{73} - \frac{34}{65} + \frac{72}{73} - \frac{39}{65} = (\frac{72}{73} + \frac{72}{73}) - (\frac{34}{65} + \frac{39}{65}) = \frac{144}{73} - \frac{73}{65} = \frac{144}{73} - 1 = \frac{144 - 73}{73} = \frac{71}{73}$ 3) $\frac{10}{21} - \frac{4}{15} - \frac{5}{14} = \frac{100 - 56 - 75}{210} = \frac{-31}{210}$ 4) $(\frac{7}{6} - \frac{1}{12} + \frac{1}{36}) \cdot \frac{72}{34} = (\frac{42 - 3 + 1}{36}) \cdot \frac{72}{34} = \frac{40}{36} \cdot \frac{72}{34} = \frac{10}{9} \cdot \frac{36}{17} = \frac{10 \cdot 4}{17} = \frac{40}{17} = 2\frac{6}{17}$ 5) $2\frac{4}{9} : (\frac{2}{3} - \frac{2}{7}) = \frac{22}{9} : (\frac{14 - 6}{21}) = \frac{22}{9} : \frac{8}{21} = \frac{22}{9} \cdot \frac{21}{8} = \frac{11 \cdot 7}{3 \cdot 4} = \frac{77}{12} = 6\frac{5}{12}$ 6) $\frac{74 - 26}{25} : \frac{48}{(-5)} \cdot \frac{15}{4} = \frac{48}{25} : (\frac{48}{-5} \cdot \frac{15}{4}) = \frac{48}{25} : (-12 \cdot 3) = \frac{48}{25} : (-36) = \frac{48}{25} \cdot (-\frac{1}{36}) = -\frac{4}{25 \cdot 3} = -\frac{4}{75}$ 7) $\frac{5}{9} : (\frac{7}{9} + \frac{11}{18}) = \frac{5}{9} : (\frac{14 + 11}{18}) = \frac{5}{9} : \frac{25}{18} = \frac{5}{9} \cdot \frac{18}{25} = \frac{1 \cdot 2}{1 \cdot 5} = \frac{2}{5}$ 8) $72 \cdot (\frac{19}{24} - \frac{7}{12} + \frac{3}{8}) = 72 \cdot (\frac{19 - 14 + 9}{24}) = 72 \cdot \frac{14}{24} = 3 \cdot 14 = 42$ 9) $\frac{9}{14} : \frac{5}{2} - \frac{4}{35} = (\frac{9}{14} \cdot \frac{2}{5}) - \frac{4}{35} = \frac{9}{35} - \frac{4}{35} = \frac{5}{35} = \frac{1}{7}$ 10) $\frac{7}{36} \cdot (-\frac{6}{50}) + \frac{29}{36} \cdot (-\frac{6}{50}) = (-\frac{6}{50}) \cdot (\frac{7}{36} + \frac{29}{36}) = (-\frac{3}{25}) \cdot \frac{36}{36} = -\frac{3}{25} = -0.12$