Ответ:

  1. 4 · □ = 32: 32 : 4 = 8.
  2. 9 · □ = 27: 27 : 9 = 3.
  3. □ · 4 = 24: 24 : 4 = 6.
  4. 36 : □ = 9: 36 : 9 = 4.
  5. 18 : □ = 2: 18 : 2 = 9.
  6. 28 : □ = 7: 28 : 7 = 4.
  7. 43 − 40 + □ = 12: 3 + □ = 12, значит, □ = 9.
  8. 38 − □ + 49 = 79: 87 − □ = 79, значит, □ = 8.
  9. 68 − □ − 20 = 40: 48 − □ = 40, значит, □ = 8.

Ответ: 8, 3, 6; 4, 9, 4; 9, 8, 8.