2.85×0.4-0.35×0.4简便计算=0.4×(2.85-0.35)=0.4×2.5=1
2.85×0.4-0.35×0.4简便计算=(2.85-0.35)x0.4=2.5x0.4=1
=0.4×(2.85-0.35)=0.4×2.5=1