1: =80*24-27*30
=1920-810=1110
2: =7*10^3-25*100
=100*(7*10-25)
=4500
3: \(=74\cdot100+100\cdot26-70\cdot100\)
=100(74+26-70)
=30*100=3000
4: \(=31\cdot7^2\left(15\cdot4-40\right)=31\cdot7^2\cdot20=30380\)
5: \(=11\cdot100+89\cdot100-90\cdot100\)
=100(11+89-90)
=1000