A shopkeeper sold an article at $100 with 15% profit. Then find its cost price? Choose the correct choice from the following options.
A) $ 120 B) $ 100 C) $ 91 D) $ 87 E) $ 69

Rationale: "cost price = selling price * 100 / ( 100 + profit ) c . p . = 100 * 100 / 115 = $ 87 ( approximately ) answer is d"
Answer: D