A total of $60,000 was invested for one year. But of this amount earned simple annual interest at the rate of x percent per year, and the rest earned simple annual interest at the rate of y percent per year. If the total interest earned by the $60,000 for that year was $4080, what is the value of x?

(1) x= (3/4)y

(2) the ratio of the amount that earned interest at the rate of x percent per year to the amount that earned interest at the rate of y percent per year was 3 to 2

Answer: C

為何不是d??

分别推，推不出来，结合起来才能算出来。设两部分amount分别为A，B。

Ax+By=4080

A+B=60000

由2. --> A:B=3:2, 得出A，B,但是x,y算不出来。

由1，x=(3/4)y,方程联立，就可以得出x,y了。

大概你没有看清第二个条件的内容吧