Ответ:

  1. \(\frac9{28}\cdot8=\frac{72}{28}=\frac{18}{7}=2\frac47\).
  2. \(\frac7{24}\cdot16=\frac{112}{24}=\frac{14}{3}=4\frac23\).
  3. \(42\cdot\frac47=6\cdot4=24\).
  4. \(\frac6{19}\cdot57=6\cdot3=18\).