A bookseller sells his books at a 20% markup in price. If he sells a book for $36.00, how much did he pay for it?
Pick one
A) $ 34.40  B) $ 34.00  C) $ 32.00  D) $ 30.00  E) $ 35.00

Rationale: "let the cost price of book = x selling price of book = 36 $ markup % = 20 ( 120 / 100 ) x = 36 = > x = 30 answer d"
Answer: D