设原来甲仓库是乙仓库的x,把乙仓库看做1
(1-1/4)x+(1+x/4)*(1/4)=(1+x/4)*(1-1/4)
3x/4+1/4+x/16=3/4+3x/16
9x+4+x=9+3x
7x=5
x=5/7