大牛 来帮 解一 数学题啊

pwj8899

Alice's task-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 that portion of  her monthly take-home pay that she did not save. If 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?

hansomecd

alice一个月赚N元到手（take-home pay）每个月都回存起来一部分M元。到年底了，alice一共存的钱（12个M元），是她每个月花的钱（N-M）的3倍。假设她只有这个经济来源，那么她每个月存的钱占了多少比。

12m=3（n-m） 算出m/n就好了

请把走出GMAT困境板块的那贴删掉。。。