The ratio between the sale price and the cost price of an article is 9:5. What is the ratio between the profit and the cost price of that article?
Choices:
A) 23  B) 1 : 2  C) 4 : 5  D) 3 : 5  E) 25

Rationale: "c . p . = rs . 5 x and s . p . = rs . 9 x . then , gain = rs . 4 x required ratio = 4 x : 5 x = 4 : 5 c"
Answer: C