In this question, two things have been asked, but the funny thing is that the answer to both the questions can be reached following a single procedure. The information's that have already been provided in the question are:
Number of books Samantha has = 45
Number of books that can be packed in a box = 7
Number of boxes that can be packed with 7 books can be found by dividing the total number of books by the number of books in a box. also the remainder that will be left is actually the number of books that were left after packing the boxes.
Then
Number of boxes containing 7 books each = 45/7
= 6 3/7
So 6 boxes can be packed with 7 books each and 3 books will be left behind.