###Human: Cody was reading through his favorite book series.  The series was 54 books in total.  If Cody read 6 books the first week, and 3 books the second week and then 9 books every week after that.  How many weeks did it take Cody to read his series?, ### Assistant: Cody needs to read 54 books - 6 books - 3 books = 45 books.
Cody read 9 books each week after = 45 books / 9 books per week = 5 weeks.
Cody read for 1 week + 1 week + 5 weeks = 7 weeks total. 
 So the answer is :  7