Online Book Merchants offers premium customers $1$ free book with every purchase of $5$ or more books and offers $2$ free books with every purchase of $8$ or more books. It offers regular customers $1$ free book with every purchase of $7$ or more books, and offers $2$ free books with every purchase of $12$ or more books.

Write a set of nested if$/$else statements that assigns freeBooks the appropriate value based on the values of the bool variable isPremiumCustomer and the int variable nbooksPurchased.