以绳测井深,3折如井底,井口余13/3,如果4折如井底,井口上只余1米,求井深几米?
问题描述：
以绳测井深,3折如井底,井口余13/3,如果4折如井底,井口上只余1米,求井深几米?
答
设绳子x
x/3-13/3＝4/X-1
X/12=10/3
X=40
井40/4-1＝9