Answer: 10 days
Step-by-step explanation: So if the librarian sorted at a constant rate, then they sorted the same amount of books all 6 days. If they still have 200 books left to sort, then they sorted 300 books over 6 days. This means that they sorted 50 books per day. 200 divided by 50 is 4. So it will take 4 more days to finish sorting all the books. So altogether, it will take 10 days to sort all of the books.
