42.1×0.75－0.579×25＋57.9用简便算法怎么算
问题描述：
42.1×0.75－0.579×25＋57.9用简便算法怎么算
如题
答
=42.1*0.75-57.9*0.25+57.9=42.1*0.75+57.9*(1-0.25)=42.1*0.75+57.9*0.75=100*0.75=75