=0.513*10*0.27+2.7*0.513
=0.513*(2.7+2.7)
=2.7702126.5除0.25除40=2.8*4+7.2/(1/4)=2.8*4+7.2*4=(2.8+7.2)*4=4=126.5/(1/4)/40=126.5*4/40=126.5/10=12.65