1. Вычислите: 2 1/3 : (5/8 - 7/8) + 2 * 1 1/7.

1. $2\frac{1}{3} : (\frac{5}{8} - \frac{7}{8}) + 2 \cdot 1\frac{1}{7} = 2\frac{1}{3} : (-\frac{2}{8}) + 2 \cdot \frac{8}{7} = \frac{7}{3} : (-\frac{1}{4}) + \frac{16}{7} = \frac{7}{3} \cdot (-4) + \frac{16}{7} = -\frac{28}{3} + \frac{16}{7} = -\frac{196}{21} + \frac{48}{21} = -\frac{148}{21} = -7\frac{1}{21}$ 2. $\frac{3}{4} + 3\frac{3}{5} \cdot (\frac{5}{18} - \frac{7}{24}) - \frac{1}{5} = \frac{3}{4} + \frac{18}{5} \cdot (\frac{20}{72} - \frac{21}{72}) - \frac{1}{5} = \frac{3}{4} + \frac{18}{5} \cdot (-\frac{1}{72}) - \frac{1}{5} = \frac{3}{4} - \frac{18}{360} - \frac{1}{5} = \frac{3}{4} - \frac{1}{20} - \frac{1}{5} = \frac{15}{20} - \frac{1}{20} - \frac{4}{20} = \frac{10}{20} = \frac{1}{2}$ 3. $\frac{5}{6} + \frac{10}{9} : (3 - 1\frac{17}{21}) - 1\frac{11}{30} = \frac{5}{6} + \frac{10}{9} : (3 - \frac{38}{21}) - \frac{41}{30} = \frac{5}{6} + \frac{10}{9} : (\frac{63-38}{21}) - \frac{41}{30} = \frac{5}{6} + \frac{10}{9} : \frac{25}{21} - \frac{41}{30} = \frac{5}{6} + \frac{10}{9} \cdot \frac{21}{25} - \frac{41}{30} = \frac{5}{6} + \frac{2}{3} \cdot \frac{7}{5} - \frac{41}{30} = \frac{5}{6} + \frac{14}{15} - \frac{41}{30} = \frac{25}{30} + \frac{28}{30} - \frac{41}{30} = \frac{12}{30} = \frac{2}{5}$ 4. $2\frac{1}{2} + \frac{9}{16} \cdot 1\frac{5}{27} - 3\frac{3}{28} : \frac{27}{28} = 2\frac{1}{2} + \frac{9}{16} \cdot \frac{32}{27} - \frac{87}{28} \cdot \frac{28}{27} = 2\frac{1}{2} + \frac{1}{1} \cdot \frac{2}{3} - \frac{87}{27} = 2\frac{1}{2} + \frac{2}{3} - 3\frac{6}{27} = 2\frac{1}{2} + \frac{2}{3} - 3\frac{2}{9} = 2\frac{9}{18} + \frac{12}{18} - 3\frac{4}{18} = 2\frac{21}{18} - 3\frac{4}{18} = 3\frac{3}{18} - 3\frac{4}{18} = -\frac{1}{18}$ 5. $\frac{4}{3} + (-8\frac{1}{5} + 8\frac{3}{5}) : \frac{7}{6} = \frac{4}{3} + (\frac{2}{5}) : \frac{7}{6} = \frac{4}{3} + \frac{2}{5} \cdot \frac{6}{7} = \frac{4}{3} + \frac{12}{35} = \frac{140}{105} + \frac{36}{105} = \frac{176}{105} = 1\frac{71}{105}$ 6. $\frac{16}{15} : 2 - 6\frac{1}{3} + 2\frac{1}{12} \cdot \frac{4}{5} = \frac{8}{15} - \frac{19}{3} + \frac{25}{12} \cdot \frac{4}{5} = \frac{8}{15} - \frac{19}{3} + \frac{5}{3} = \frac{8}{15} - \frac{14}{3} = \frac{8}{15} - \frac{70}{15} = -\frac{62}{15} = -4\frac{2}{15}$ 7. $\frac{3}{5} + 4\frac{1}{21} \cdot (\frac{4}{14} - \frac{3}{14}) - \frac{3}{5} = 4\frac{1}{21} \cdot \frac{1}{14} = \frac{85}{21} \cdot \frac{1}{14} = \frac{85}{294}$