Sandy bought 65 books for $1080 from one shop and 55 books for $840 from another shop. What is the average price that Sandy paid per book?  Choose the correct choice from the following answers:
A) $ 14
B) $ 16
C) $ 18
D) $ 20
E) $ 22

Rationale: "average price per book = ( 1080 + 840 ) / ( 65 + 55 ) = 1920 / 120 = $ 16 the answer is b ."
Answer: B