7.25-6.25+2.75-1.65=7.25+2.75-6.25-1.65=10-(6.25+1.65)=10-7.9=2.1
=7.25+2.75-(6.25+1.65)=10-7.9=2.1
7.25-6.25+2.75-1.65=1+2.75-1.65=1+1.1=2.1前面两个先算,后面两个一起算,最后得出结果
7.25-6.25+2.75-1.65=1+1.1=2.1