问题描述: (78.6-0.786×2.5+0.75×21.4)÷15×1997=? 1个回答 分类:数学 2014-11-08 问题解答: 我来补答 (78.6-0.786×2.5+0.75×21.4)÷15×1997=(393/5-393/500*5/2+3/4*107/5)/15*1997=(393/5-393/200+321/20)/15*1997=(393/5+2817/200)/15*1997=18537/200/15*1997=12339.463 展开全文阅读