设第二仓原来存粮Y包那么根据题意 (4500-4500x1/5)-(Y+4500x1/5)x7/8=100则Y=3100包
设第二仓原有存粮X包4500*4/5-7/8*(4500*1/5+X)=100X=3100
设第二仓原有存粮X包4500x4/5-7/8x(4500x1/5+X)=100X=3100
4500x1/5=9004500-900=3600(3600-100)÷7/8=40004000-900=3100