Ответ:

  1. \(4+1.4=5.4\).
  2. \(6.3-8=-1.7\).
  3. \(2.5\cdot0.4=1\).
  4. \(5.7:3=1.9\).
  5. \(6\cdot3+12=30\).
  6. \(16+0.1\cdot20=18\).
  7. \(8\cdot7-2.5=53.5\).
  8. \((8-1.3)\cdot0.1=0.67\).
  9. \((2+2.5)\cdot3=13.5\).
  10. \(-6-(-3.5+2.3)=-6-(-1.2)=-4.8\).
  11. \(30\cdot(2.6:13)=30\cdot0.2=6\).
  12. \((8+0.1):0.9=8.1:0.9=9\).
  13. \(7^2+2.3=49+2.3=51.3\).
  14. \(1.1^2-0.8^2=1.21-0.64=0.57\).
  15. \((1.3+4.7)^2=6^2=36\).
  16. \(18-(20:4)=18-5=13\).
  17. \(9:0.3^2=9:0.09=100\).
  18. \((0.7-1)^2=(-0.3)^2=0.09\).
  19. \((4.5+2.5)-4=7-4=3\).
  20. \(2\cdot0.3\cdot1.2=0.72\).