Ответ:

  1. Приводим к общему знаменателю: 2/5 + 1/10 = 4/10 + 1/10 = 5/10 = 1/2.

  2. 5/6 − 2/3 = 5/6 − 4/6 = 1/6.

  3. 3/4 + 7/12 = 9/12 + 7/12 = 16/12 = 4/3.

  4. 2/15 + 4/5 = 2/15 + 12/15 = 14/15.

  5. 5/7 + 3/14 = 10/14 + 3/14 = 13/14.

  6. 3/11 − 6/55 = 15/55 − 6/55 = 9/55.

  7. 1/6 − 1/9 = 3/18 − 2/18 = 1/18.

  8. 1/10 + 1/15 = 3/30 + 2/30 = 5/30 = 1/6.