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Привет! Давай решим примеры с дробями из твоего задания. 16. $1 - \frac{3}{7} - \frac{5}{8} = \frac{56 - 24 - 35}{56} = -\frac{3}{56}$ 17. $\frac{1}{4} + \frac{2}{7} - \frac{23}{28} = \frac{7 + 8 - 23}{28} = -\frac{8}{28} = -\frac{2}{7}$ 18. $\frac{1}{5} + \frac{3}{8} - \frac{39}{40} = \frac{8 + 15 - 39}{40} = -\frac{16}{40} = -\frac{2}{5}$ 19. $\frac{2}{11} + \frac{2}{5} - \frac{37}{55} = \frac{10 + 22 - 37}{55} = -\frac{5}{55} = -\frac{1}{11}$ 20. $1 + \frac{4}{7} - \frac{60}{77} = \frac{77 + 44 - 60}{77} = \frac{61}{77}$ 21. $\frac{25}{4} : \frac{6}{5} \cdot \frac{15}{8} = \frac{25}{4} \cdot \frac{5}{6} \cdot \frac{15}{8} = \frac{25 \cdot 5 \cdot 15}{4 \cdot 6 \cdot 8} = \frac{1875}{192} = \frac{625}{64} = 9 \frac{49}{64}$ 22. $\frac{24}{5} : \frac{10}{9} : \frac{4}{3} = \frac{24}{5} \cdot \frac{9}{10} \cdot \frac{3}{4} = \frac{24 \cdot 9 \cdot 3}{5 \cdot 10 \cdot 4} = \frac{648}{200} = \frac{81}{25} = 3 \frac{6}{25}$ 23. $(\frac{17}{15} - \frac{1}{12}) \cdot \frac{20}{3} = (\frac{68 - 5}{60}) \cdot \frac{20}{3} = \frac{63}{60} \cdot \frac{20}{3} = \frac{63 \cdot 20}{60 \cdot 3} = 7$ 24. $\frac{7}{2} : (\frac{7}{8} - \frac{3}{4}) = \frac{7}{2} : (\frac{7 - 6}{8}) = \frac{7}{2} : \frac{1}{8} = \frac{7}{2} \cdot 8 = 28$ 25. $\frac{2}{9} + \frac{4}{21} : \frac{3}{7} = \frac{2}{9} + \frac{4}{21} \cdot \frac{7}{3} = \frac{2}{9} + \frac{4 \cdot 7}{21 \cdot 3} = \frac{2}{9} + \frac{4}{9} = \frac{6}{9} = \frac{2}{3}$ 26. $\frac{15}{7} + \frac{9}{7} \cdot \frac{2}{3} = \frac{15}{7} + \frac{9 \cdot 2}{7 \cdot 3} = \frac{15}{7} + \frac{6}{7} = \frac{21}{7} = 3$ 27. $\frac{45}{8} : \frac{6}{5} : \frac{9}{4} = \frac{45}{8} \cdot \frac{5}{6} \cdot \frac{4}{9} = \frac{45 \cdot 5 \cdot 4}{8 \cdot 6 \cdot 9} = \frac{900}{432} = \frac{25}{12} = 2 \frac{1}{12}$ 28. $\frac{6}{5} : (\frac{9}{10} - \frac{1}{5}) = \frac{6}{5} : (\frac{9 - 2}{10}) = \frac{6}{5} : \frac{7}{10} = \frac{6}{5} \cdot \frac{10}{7} = \frac{60}{35} = \frac{12}{7} = 1 \frac{5}{7}$ 29. $\frac{22}{3} : \frac{11}{48} \cdot \frac{5}{8} = \frac{22}{3} \cdot \frac{48}{11} \cdot \frac{5}{8} = \frac{22 \cdot 48 \cdot 5}{3 \cdot 11 \cdot 8} = 2 \cdot 16 \cdot \frac{5}{8} = 2 \cdot 2 \cdot 5 = 20$