同分得 35/140,56/140,60/140,分母一样看分子大小，比较得60＞56＞35，所以大小关系为3/7＞2/5＞1/4
1/4=35/1402/5=48/1403/7=60/1403/7>2/5>1/4
1/4=35/140,2/5=56/140,3/7=60/140所以3/7>2/5>1/4
1/4=35/1402/5=56/1403/7=60/140∴1/4＜2/5＜3/7
