(1).2005-395+605
=2005+605-395
=2610-400+5
=2210+5
=2215
(2).1.25*1.5*8*15分之1
=(1.25*8)*(1.5*1/15)
=10*0.1
=1
（3）.86分之85*87
=85/86*(86+1)
=85+85/86
=85又85/86
（4）.8分之3*8.4+2又5分之3*0.375-8分之3
=3/8*(8.4+2.6-1)
=3/8*10
=3.75