15.87-13.67+17.3
=2.2+17.3
=19.5
15.87+17.3-13.67=15.87-13.67+17.3=2.2+17.3=19.5
计算过程如下原式＝15.87-13.67+17.3＝2.2+17.3＝19.5
简便计算如下:15.87+17.3-13.67=15.87-13.67+17.3=2.2+17.3=19.5
