计算 2/5+3/4+2/3= 2/3-(1/4+1/5)= 25/28-(3/7+5/14)=

问题描述:

计算 2/5+3/4+2/3= 2/3-(1/4+1/5)= 25/28-(3/7+5/14)=

2/5+3/4+2/3=24/60+45/60+40/60=89/60=1又29/60
2/3-(1/4+1/5)=40/60-15/60-12/60 =13/60
25/28-(3/7+5/14)= 25/28-12/28-10/28=3/28