1. 9*5=45, 2.-24÷6=4, 3.-24÷2=12, 4.-45-12=33
2.1.-24÷3=4, 2.-40-4=36, 3.-36÷4=9, 4.-90-9=81
3.1.-3*4=12, 2.-7*5=35, 3.-12+35=47
4.1.-27+9=36, 2.-36÷4=9, 3.-9*5=45
5.1.-50-23=27, 2.-27÷3=9, 3.-8*5=40, 4.-40+9=49
6.1 26-21=5, 2.-6*5=30, 3.-30+5=35, 4.-30÷5=6
7.-