Ответ:

  1. 72 + 23 = 95; 48 + 56 = 104.
  2. 56 + 34 = 90; 45 + 8 = 53.
  3. 75 − 16 = 59; 46 − 14 = 32.
  4. 45 + 12 + 35 = 45 + 35 + 12 = 92; 77 − (40 + 17) = 77 − 57 = 20.