[問題] GMAT prep

[cutefox0108]

Alice's take-home pay last year was the same each month,and she saved the same fraction of her take -home pay each month.The total amount of money that she had saved at the end of the year was 3 times the amount of money portion of her monthly take -home pat that she did not saved. all the money that she saved last year was from her take -home pay,what fraction of her take-home pay did she save each month?

A.1/2
B.1/3
c.1/4
D.1/5
E.1/6
answer D
其實題目有點不太懂~~拜託請各位大神幫幫我~~
我覺ㄉ題目是在問
Alice 存ㄉ錢是沒存ㄉ錢ㄉ三倍,請問A每月存薪資的多少百分比
我選1/4,因為三倍而猜ㄉ

[Emmi]

1/x * 12 = 3(1-1/x)

(每個月存1/x比例的錢)*(存了12個月) = 3倍的 (每個月未存的錢)

得 x=5 ,answer=> 1/5

[pimi]

看了大大的解釋
感覺自己真是錯的離譜,但是又不知道自己是哪裡錯了（真是糟到不行～）
我是這樣想的, 存的是沒存的3倍, 所以Alice所有賺的錢可以看成4(存的加上沒存＝賺的錢)
然後存的是4中佔3, 所以每年存的錢對上賺的錢比例:3/4,問每個月存的錢對上賺的錢的比例
所以把存的錢＊1/12---->3*1/12=1/4
在對上賺的錢＝(1/4)/4=1/16
想請問我到底哪裡錯了 @ @