请教一个数学问题，题目什么意思啊？

luclily

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 $4,080, 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.

                  

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.

B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.

C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

D. EACH statement ALONE is sufficient.

E. Statements (1) and (2) TOGETHER are NOT sufficient.

答案是D，这题到底是说把一笔钱分成2比放2处投资，一处利率X一处利率Y，还是说把60000放一起投资利率一开始是X后来是Y啊？请NN们帮我解答一下

luclily

谁来帮我解答一下啊

carlotta

把一笔钱分成2比放2处投资，一处利率X一处利率Y

我觉得是这个意思

maoruibei

annually simple interest would not be changed in that year

maoruibei

为什么选D,怎么会选D'?

设放x的量为M

的方程

M*X +(60,000-M) *Y= 4080  三个未知数 需要三个方程啊