求助一道PREP数学题！！！！！！

aglair萱

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 years 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?
A 1/2
B 1/3
C 1/4
D 1/5
E 1/6

Vevey

设Alice每个月总收入为y, 每个月save x,
那么一年save 12x
12x=3(y-x)
x/y=1/5  选D

aglair萱

设Alice每个月总收入为y, 每个月save x,
那么一年save 12x
12x=3(y-x)
x/y=1/5  选D

-- by 会员 Vevey (2011/5/7 18:24:39)

谢谢！！！懂了！！！！！！