一道GMAT prep软件上的题目，请大家帮忙告诉我怎么做

rabbitaoy

Each employee on a certain task force is either a manager or director.  What percent of the employees on the task force are directors?
1. The average salary of the managers on the task force is 5000 less than the average of all employees on the task force
2. The average salary of the directors on the task force is 15,000 greater than the average salary of all employees on the task force

Answer is C.

我怎么想也想不出来，大家试试看。

sunfengchuan

设所有EMPLOYEE平均工资为X，manager人数为M，Director人数为D,总人数为T
m+d=t
m(x-5000)+d(x+15000)=tx
这两个方程能得出一个关系来
5000m=15000d
所以就能求出来了。

gesteven

是啊，做的时候就是给设错了……