Ответ:

  1. \(42+19=61\)
  2. \(3\cdot7=21\)
  3. \(99-66=33\)
  4. \(3\cdot9=27\)
  5. \(27+48=75\)
  6. \(16:2=8\)
  7. \(31+19=50\)
  8. \(21:3=7\)