80.5÷1.25=(80.5×0.8)÷(1.25×0.8)=(80+0.5)×0.8÷1=80×0.8+0.5×0.8=64+0.4=64.4
=80.5/(0.5x2.5)=80.5/0.5/2.5=161/2.5=161/(0.5x5)=161/0.5/5=322/5=64.4
80.5÷1.25=80.5÷(10÷8)=80.5*8÷10=644÷10=64.4