Answer: 13n + 20
Step-by-step explanation:
The cost of each book is $13. That means that if you end up buying "n" books, cost would be:
= Cost of each book * number of books
= 13 * n
= 13n
You would also get charged a flat rate for shipping of $20 which would be added to the above cost to bring a total of:
= 13n + 20