1.4.5-3/5
=45/10-6/10
=39/10
=3.9(米)
2.1-3/5=2/5
5.5*(1-3/5)=2.2(米)
3. 5*6/5*4/3
=8(吨)
4.39*1/13*2/3
=3*2/3
=2(千克)