Ответ:

  1. 4 2/9 + 5 2/3 − 1 4/9 = 4 2/9 + 5 6/9 − 1 4/9 = 9 8/9 − 1 4/9 = 8 4/9.
  2. 5 3/5 − 2 6/11 + 3 3/5 = 8 6/5 − 2 6/11 = 8 1 1/5 − 2 6/11 = 8 11/55 − 2 30/55 = 5 36/55 = 5 36/55.
  3. 20 − 3 8/15 + 10 4/5 = 16 7/15 + 10 12/15 = 27 4/5.