Ответ:

  1. 12 − (4 + 5) = 12 − 9 = 3.
  2. 6 + (4 − 2) = 6 + 2 = 8.
  3. 9 + (8 − 3) = 9 + 5 = 14.
  4. 17 − (2 + 4) = 17 − 6 = 11.
  5. (5 − 2) + (7 − 4) = 3 + 3 = 6.