方法一:总共的:75÷(1-3/4)
=75÷1/4
=75×4
=300(吨)
运走的:300-75=225(吨)
75÷225=1/3
方法二:1-3/4=1/4
1/4÷3/4
=1/4×4/3
=1/3
祝您学习进步!
望采纳!