原式=0.45×5.8+(0.45*10)×0.58=0.45*5.8+0.45*(10*0.58)=0.45*5.8*2=0.9*5.8=(1-0.1)*5.8=5.8-0.58=5.22
=4.5*0.58+4.5*0.58=2*4.5*0.58=9*0.58=5.22