4分之1比2分之10 =(1/4):(10/2) =1:20 35比0.65; =35:0.65 =3500:65 =700:13 400千克比3分之2吨; =400:(2/3)*1000 =1200:2000 =3:5 15分比1(时); =15:1*60 =15:60 =1:4