Ответ:

  1. 1 − 8/19 = 11/19.
  2. 6 − 9/14 = 5 + 5/14 = 5 5/14.
  3. 7 − 1 8/9 = 5 + 1/9 = 5 1/9.
  4. 11 − 4 = 7.