5.5*17.3+6.7*5.5=5.5*(17.3+6.7)=5.5*24=132 1.5*105 =1.5*(100+5)=1.5*100+1.5*5=150+7.5=157.5 9.07-22.78除以3.4 =9.07-6.7=2.37 3.8+4.92+2.1+4.2 =(3.8+4.2)+(4.92+2.1)=8+7.02=15.02