16. Вычислите: 8/9 - 3/8 : 27/28

16. $\frac{8}{9} - (\frac{3}{8} : \frac{27}{28}) = \frac{8}{9} - (\frac{3}{8} \cdot \frac{28}{27}) = \frac{8}{9} - \frac{7}{18} = \frac{16-7}{18} = \frac{9}{18} = \frac{1}{2}$ 17. $(\frac{16}{21} : \frac{12}{35}) - 2 = (\frac{16}{21} \cdot \frac{35}{12}) - 2 = \frac{20}{9} - 2 = \frac{20-18}{9} = \frac{2}{9}$ 18. $(\frac{35}{24} : \frac{15}{32}) - 3 = (\frac{35}{24} \cdot \frac{32}{15}) - 3 = \frac{28}{9} - 3 = \frac{28-27}{9} = \frac{1}{9}$ 19. $2 - (\frac{15}{28} : \frac{10}{21}) = 2 - (\frac{15}{28} \cdot \frac{21}{10}) = 2 - \frac{9}{8} = \frac{16-9}{8} = \frac{7}{8}$ 20. $(18 \cdot \frac{5}{81}) - \frac{2}{3} = \frac{10}{9} - \frac{2}{3} = \frac{10-6}{9} = \frac{4}{9}$ 21. $(24 \cdot \frac{3}{64}) - \frac{3}{4} = \frac{9}{8} - \frac{3}{4} = \frac{9-6}{8} = \frac{3}{8}$ 22. $(\frac{18}{35} : 12) + \frac{1}{10} = \frac{3}{70} + \frac{1}{10} = \frac{3+7}{70} = \frac{10}{70} = \frac{1}{7}$ 23. $(\frac{27}{40} : 18) + \frac{9}{16} = \frac{3}{80} + \frac{9}{16} = \frac{3+45}{80} = \frac{48}{80} = \frac{3}{5}$