有更好的方法吗

DS, in a work force, the empolyees are either managers or directors. What is the percentage of directors?

a) the average salary for manager is $5,000 less than the total average salary

b) the average salary for directors is $15,000 more than the total average salary

answer is C

似乎可以算出来,但是很麻烦,请教有没有其他方法

谢谢

很想知道大家的算法　　谢谢啦

我的做法，列方程，解方程,不知道算不算麻烦的方法

设director比例X,那么manager=1-X

设total average salary=Y

条件A推出the average salary for manager=(Y-5000)

条件B推出the average salary for director=(Y+15000)

下面算总合

Total manager salary + Total director salary = total average salary

(Y-5000)*(1-X) + (Y+15000)*X = Y*1

简化以后得出 X=1/4=0.25 解唯一

谢谢啊 比我的方法简单 !我设了3个未知数呢