Ответ:

  1. 64 + 29 + 61 + 36 = (64 + 36) + (29 + 61) = 100 + 90 = 190.
  2. 120 + 65 + 15 = 120 + 80 = 200.
  3. 460 + 380 + 20 = 460 + 400 = 860.