Ответ:

  1. 2 + 4 + 7 + 4 = 17
  2. 7 + 4 + 9 + 4 = 24
  3. 9 − 4 + 9 + 3 = 17
  4. 5 + 7 + 3 + 9 = 24
  5. 8 + 6 + 1 + 9 = 24
  6. 4 + 3 + 6 + 2 = 15
  7. 7 − 2 + 9 + 1 = 15
  8. 3 + 9 + 3 + 9 = 24
  9. 6 − 2 + 8 + 9 = 21
  10. 7 + 8 + 5 + 1 = 21
  11. 3 + 6 − 4 + 9 = 14
  12. 5 + 9 + 8 + 3 = 25