想问一下这道数学题结果是怎么得来的？

legnawen

Q28:

Last Sunday a certain store sold copies of Newspaper A for $1.00 each and copies of Newspaper B for $1.25 each, and the store sold no other newspapers that day.If r percent of the store’s revenues from newspaper sales was from Newspaper A and if p percent of the newspapers that the store sold were copies of newspaper B, which of the following expresses r in terms of p?



A.100p / (125 – p)

B.150p / (250 – p)

C.300p / (375 – p)

D.400p / (500 – p)

E.500p / (625 – p)

Answer: D

bloomers

是不是缺了一个条件啊

legnawen

缺了什么条件啊？！
Here is the working
Total Revenue = p/100 + (100 -p)1.25/100

r/100 {p/100 + (100-p)1.25/100} = p/100
r (125 - 0.25p) = 100p
r = 100p/(125 - 0.25p)
= 400p(500 - p)
这是网上的答复
但是个人觉得不妥

sbjqbS

Total Revenue = p/100 + (100 -p)1.25/100

r/100 {p/100 + (100-p)1.25/100} = p/100
r (125 - 0.25p) = 100p
r = 100p/(125 - 0.25p)
= 400p(500 - p)

卖p%的是B报纸啊！为什么p%乘以的是A报纸的单价（1美元）？？
方法是没错，但是数字有问题。
是不是题目给错了？P%应该是A报纸卖的份额？？

legnawen

我也搞不懂，这是GWD试题里的答案，几乎每套试题都有这么1~2题让自己感觉很纠结的