8.6×18-8又3/5×8
=8.6×(18-8)
=8.6×10
=865.39+2/7+3.61+1 5/7是多少？（用简便方法计算）5.39+2/7+3.61+1又5/7=(5.39+3.61)+(2/7+1又5/7)=9+2=11