Ответ:

  1. \(4{,}8=4\dfrac{8}{10}=4\dfrac{4}{5}\);
  2. \(0{,}21=\dfrac{21}{100}\);
  3. \(5{,}87=5\dfrac{87}{100}\);
  4. \(75{,}9=75\dfrac{9}{10}\);
  5. \(0{,}08=\dfrac{8}{100}=\dfrac{2}{25}\);
  6. \(2{,}080=2\dfrac{80}{1000}=2\dfrac{2}{25}\).

Ответ: 1) \(4\dfrac{4}{5}\); 2) \(\dfrac{21}{100}\); 3) \(5\dfrac{87}{100}\); 4) \(75\dfrac{9}{10}\); 5) \(\dfrac{2}{25}\); 6) \(2\dfrac{2}{25}\).