Ответ:

  1. \(70+(33-20)=70+13=83\).
  2. \(60-(13+7)=60-20=40\).
  3. \(50-(18+12)=50-30=20\).
  4. \(20+(45-25)=20+20=40\).
  5. \(24-3+5=21+5=26\).
  6. \(35-2+7=33+7=40\).
  7. \(3+47-30=50-30=20\).
  8. \(80-60-5=20-5=15\).
  9. \(18+8=26\).
  10. \(56+7=63\).
  11. \(55+6=61\).
  12. \(19+9=28\).

Ответ: 83; 40; 20; 40; 26; 40; 20; 15; 26; 63; 61; 28.