Subject: mathqa
Question: bookman purchased 55 copies of a new book released recently , 10 of which are hardback and sold for $ 20 each , and rest are paperback and sold for $ 10 each . if 14 copies were sold and the total value of the remaining books was 460 , how many paperback copies were sold ?
Option: 
A: 13
B: 11
C: 10
D: 9
Answer: D