求解一道题

greates

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)

                                     500p / (625 – p)
答案是D  求过程

myice

题目不对吧，应该是
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 A,which of the following expresses r in terms of p?
这样算出来是D呢~~~

liuzhenlin

总的revenue是 T=1*m+1.25*n, 其中m是A的份数，n是B的份数
由题可知  r/100 * T= 1*m----------1

                p/100*T=1.25*n----------2
1+2得：r/100*T+p/100*T=T， 消去T

所以r+p=100
所以D对。   应该是这样

aobailing

p是份数百分比， p/100*T=1.25*n----------2   不成立

norgar

不对呀 r+p=100是前提   。。。

俺也不懂。。同求助