Problem Solving

试题详情

题目:

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?

选项:

A、100p / (125 -  p )
B、150p / (250 -  p )
C、300p / (375 -  p )
D、400p / (500 -  p )
E、500p / (625 -  p )

答案:

D

提问:

解不出答案 我列的式子是r/100=y/(x+1.25y) P/100=y/(x+y)
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