Ответ:

  1. 8 + 7 − 9 = 15 − 9 = 6
  2. 5 + 6 − 8 = 11 − 8 = 3
  3. 13 − 5 + 4 = 8 + 4 = 12
  4. 14 − 6 + 2 = 8 + 2 = 10
  5. 5 + (16 − 8) = 5 + 8 = 13
  6. 7 + (15 − 9) = 7 + 6 = 13