138又4分之1+23.3*（2-4分之3）-1.25*38+(1+0.25)*28.7

138又4分之1+23.3*（2-4分之3）-1.25*38+(1+0.25)*28.7
=137+1.25+23.3*1.25-1.25*38+1.25*28.7
=137+1.25*(1+23.3-38+28.7)
=137+1.25*15
=137+18.75
=155.75