18.6/2.5/0.4
=18.6÷2.5÷0.4
=18.6÷（2.5×0.4）
=18.6÷1=18.6
3.5/0.125
=7/2÷1/8
=28
8.37-3.25-(1.37+17.5)
=8.37-1.37-3.25-17.5
=7-17.5-3.25
=-10.5-3.25=-13.75