Ответ:

  1. 5 + 3 + 9 = 8 + 9 = 17.
  2. 20 − 5 − 6 = 15 − 6 = 9.
  3. 3 + (10 − 2) = 3 + 8 = 11.
  4. 8 + 7 − 6 = 15 − 6 = 9.
  5. 4 + 7 − 9 = 11 − 9 = 2.
  6. 11 − (8 + 3) = 11 − 11 = 0.
  7. 11 + 4 − 8 = 15 − 8 = 7.
  8. 9 + 8 − 10 = 17 − 10 = 7.
  9. 5 + (12 − 4) = 5 + 8 = 13.