100-(28.4+32.05)=100-(28+0.4+32+0.05)=100-(28+32+0.4+0.05)=100-(60+0.45)=100-60-0.45=40-0.45=39.55
=100-60.45=100-60-0.45=40-0.45=39+1-0.45=39.55
简便计算如下100-28.4-32.05＝71.6-32.05＝39.55
