Rahim bought 50 books for Rs.1000 from one shop and 40 books for Rs.800 from another. What is the average price he paid per book ?
Choose the correct choice from the following answers
A) 28	B) 20	C) 27	D) 29	E) 21

Rationale: "average price per book = ( 1000 + 800 ) / ( 50 + 40 ) = 1800 / 90 = rs . 20 answer : b"
Answer: B