(78.6-0.786*25+75%*21.4)*1997
=(78.6×1-78.6×0.25+0.75×21.4)×1997
=[78.6×(1-0.25)+0.75×21.4]×1997
=(78.6×0.75+21.4×0.75)×1997
=0.75×(78.6+21.4)×1997
=75×1997
=149775=(78.6×0.75+21.4×0.75)×1997是什么意思？前面1-0.25=0.75呀 78.6×0.75+21.4×0.75=0.75(78.6+21.4)=0.75×100=75我的意思是：它本来不是+0.75×21.4吗？怎么变成了+21.4×0.75？0.75×21.4和21.4×0.75不是一样吗