Answer: There are 59850 ways to chose the display.
Explanation:
Since we have given that
Number of paperback publishers = 5
Number of titles each box contains = 21
Number of books display = 4
Number of publishers he needed = 3
So, the number of ways to select the 3 publishers from 5 is given by
Number of ways to select the books from the different books is given by
Hence, total number of ways that the display can be chosen is given by
Hence, there are 59850 ways to chose the display.