A, B, and C have a total of 100 books. When A's original number is divided by B's original number, and C's original number is divided by A's original number, the quotient is 5 and the remainder is 1. So how many books does B have?
甲、乙、丙共有100本．甲的本数除以乙的本数，丙的本数除以甲的本数，商都是5，余数也都是1．那么乙有多少本书．
<result>3</result>