5(1)班人数比5(2)班多五分之二,则5(2)班比5(1)班少几分之几

问题描述:

5(1)班人数比5(2)班多五分之二,则5(2)班比5(1)班少几分之几

x=(1+2/5)y=7/5*y,
则y=5/7*x=(1-2/7)x,
即少2/7.