A certain library charges a flat fee of $5 for any overdue book for the first x days the book is overdue, and an additional fee of m dollars per day for every day after x that the book is overdue. What is the fee for a book that is 12 days overdue?

Answer: 5 (x > 12) or 5 + m (12 - x) (x < 12)

Step-by-step explanation:

flat fee $5 for first x days +

m dolars per day after x days

So, if x > 12, for 12 days the fee is $5 because it is a flat fee that do not depend of the numbers of day.

But, we do not know how many days x is, so

if x < 12, a person will pay, for 12 days, the m times the difference of the days passed x:

5 + m (12-x)