Ответ:

  1. а) \(7\frac{2}{9}:4\frac{1}{3}\cdot9=\frac{65}{9}:\frac{13}{3}\cdot9=\frac{65}{9}\cdot\frac{3}{13}\cdot9=15\).
  2. б) \(5\frac{3}{7}:\frac{8}{21}:2\frac{3}{8}=\frac{38}{7}\cdot\frac{21}{8}\cdot\frac{8}{19}=6\).
  3. в) \(1\frac{11}{21}\cdot3\frac{8}{9}:1\frac{7}{9}=\frac{32}{21}\cdot\frac{35}{9}:\frac{16}{9}=\frac{32}{21}\cdot\frac{35}{9}\cdot\frac{9}{16}=\frac{10}{3}=3\frac{1}{3}\).
  4. г) \(\frac{5}{6}\cdot\frac{6}{11}:1\frac{1}{11}=\frac{5}{11}:\frac{12}{11}=\frac{5}{12}\).

Ответ: а) \(15\); б) \(6\); в) \(3\frac{1}{3}\); г) \(\frac{5}{12}\).