20x1.9-1.8
=38-(2-0.2)
=38-2+0.2
=36+0.2
=36.2
得数是36.2，具体计算过程如下：
解：原式=38-1.8 =（36+2）-1.8 =36+（2-1.8） =36+0.2 =36.2
配图简便计算
