Вариант 2. 11. \(\frac{8}{15}\cdot(\frac{7}{8}+\frac{11}{16})\) 12. \(\frac{9}{10}\cdot(\frac{11}{12}-\frac{2}{9})\) 13.:39 \(\frac{7}{11}\cdot(\frac{11}{14}-\frac{1}{6})\) 14. \(\frac{24}{49}:\frac{6}{7}+\frac{1}{14}\) 15. \(5\frac{4}{6}:\frac{16}{9}:\frac{16}{21}\) 16. \(8\frac{3}{9}-\frac{27}{8}:\frac{27}{28}\) 17. \(16\frac{16}{21}:\frac{12}{35}-2\) 18: \(35\frac{15}{24}:\frac{15}{32}-3\) 19. \(2\frac{15}{28}:\frac{10}{21}\) 20. \(18\frac{5}{81}-\frac{2}{3}\)

Решим примеры.

1. \(\frac{8}{15} \cdot (\frac{7}{8} + \frac{11}{16}) = \frac{8}{15} \cdot (\frac{7 \cdot 2}{8 \cdot 2} + \frac{11}{16}) = \frac{8}{15} \cdot (\frac{14}{16} + \frac{11}{16}) = \frac{8}{15} \cdot \frac{25}{16} = \frac{8 \cdot 25}{15 \cdot 16} = \frac{1 \cdot 5}{3 \cdot 2} = \frac{5}{6}\)
2. \(\frac{9}{10} \cdot (\frac{11}{12} - \frac{2}{9}) = \frac{9}{10} \cdot (\frac{11 \cdot 3}{12 \cdot 3} - \frac{2 \cdot 4}{9 \cdot 4}) = \frac{9}{10} \cdot (\frac{33}{36} - \frac{8}{36}) = \frac{9}{10} \cdot \frac{25}{36} = \frac{9 \cdot 25}{10 \cdot 36} = \frac{1 \cdot 5}{2 \cdot 4} = \frac{5}{8}\)
3. \(\frac{7}{39} \cdot (\frac{11}{14} - \frac{1}{6}) = \frac{7}{39} \cdot (\frac{11 \cdot 3}{14 \cdot 3} - \frac{1 \cdot 7}{6 \cdot 7}) = \frac{7}{39} \cdot (\frac{33}{42} - \frac{7}{42}) = \frac{7}{39} \cdot \frac{26}{42} = \frac{7 \cdot 26}{39 \cdot 42} = \frac{1 \cdot 2}{3 \cdot 6} = \frac{2}{18} = \frac{1}{9}\)
4. \(\frac{24}{49} : \frac{6}{7} + \frac{1}{14} = \frac{24}{49} \cdot \frac{7}{6} + \frac{1}{14} = \frac{24 \cdot 7}{49 \cdot 6} + \frac{1}{14} = \frac{4 \cdot 1}{7 \cdot 1} + \frac{1}{14} = \frac{4}{7} + \frac{1}{14} = \frac{4 \cdot 2}{7 \cdot 2} + \frac{1}{14} = \frac{8}{14} + \frac{1}{14} = \frac{9}{14}\)
5. \(5\frac{4}{6} : \frac{16}{9} : \frac{16}{21} = \frac{5 \cdot 6 + 4}{6} : \frac{16}{9} : \frac{16}{21} = \frac{34}{6} : \frac{16}{9} : \frac{16}{21} = \frac{34}{6} \cdot \frac{9}{16} \cdot \frac{21}{16} = \frac{34 \cdot 9 \cdot 21}{6 \cdot 16 \cdot 16} = \frac{17 \cdot 3 \cdot 21}{1 \cdot 16 \cdot 16} = \frac{1071}{256} = 4\frac{47}{256}\)
6. \(8\frac{3}{9} - \frac{27}{8} : \frac{27}{28} = 8\frac{1}{3} - \frac{27}{8} \cdot \frac{28}{27} = \frac{8 \cdot 3 + 1}{3} - \frac{1}{2} \cdot \frac{7}{1} = \frac{25}{3} - \frac{7}{2} = \frac{25 \cdot 2}{3 \cdot 2} - \frac{7 \cdot 3}{2 \cdot 3} = \frac{50}{6} - \frac{21}{6} = \frac{29}{6} = 4\frac{5}{6}\)
7. \(16\frac{16}{21} : \frac{12}{35} - 2 = \frac{16 \cdot 21 + 16}{21} : \frac{12}{35} - 2 = \frac{352}{21} : \frac{12}{35} - 2 = \frac{352}{21} \cdot \frac{35}{12} - 2 = \frac{352 \cdot 35}{21 \cdot 12} - 2 = \frac{88 \cdot 5}{3 \cdot 3} - 2 = \frac{440}{9} - 2 = 48\frac{8}{9} - 2 = 46\frac{8}{9}\)
8. \(35\frac{15}{24} : \frac{15}{32} - 3 = \frac{35 \cdot 24 + 15}{24} : \frac{15}{32} - 3 = \frac{855}{24} : \frac{15}{32} - 3 = \frac{855}{24} \cdot \frac{32}{15} - 3 = \frac{855 \cdot 32}{24 \cdot 15} - 3 = \frac{285 \cdot 4}{3 \cdot 5} - 3 = \frac{1140}{15} - 3 = 76 - 3 = 73\)
9. \(2\frac{15}{28} : \frac{10}{21} = \frac{2 \cdot 28 + 15}{28} : \frac{10}{21} = \frac{71}{28} : \frac{10}{21} = \frac{71}{28} \cdot \frac{21}{10} = \frac{71 \cdot 21}{28 \cdot 10} = \frac{71 \cdot 3}{4 \cdot 10} = \frac{213}{40} = 5 \frac{13}{40}\)
10. \(18\frac{5}{81} - \frac{2}{3} = 18\frac{5}{81} - \frac{2}{3} = 18\frac{5}{81} - \frac{2 \cdot 27}{3 \cdot 27} = 18\frac{5}{81} - \frac{54}{81} = 17\frac{81 + 5}{81} - \frac{54}{81} = 17\frac{86}{81} - \frac{54}{81} = 17\frac{32}{81}\)

Ответ:

1. \(\frac{5}{6}\)
2. \(\frac{5}{8}\)
3. \(\frac{1}{9}\)
4. \(\frac{9}{14}\)
5. \(4\frac{47}{256}\)
6. \(4\frac{5}{6}\)
7. \(46\frac{8}{9}\)
8. \(73\)
9. \(5 \frac{13}{40}\)
10. \(17\frac{32}{81}\)