The Cuyahoga County Public Library charges a late fee of 10 cents for every day a book is out past its due date. Suppose you have a book that is out past is due date. Is the late fee proportional to the number of days the book is out past its due date?

If your answer above is “yes”, justify your answer by writing an equation that displays the proportional relationship. If your answer above is “no”, justify your answer by showing an example in which doubling the amount of days the book is out past its due date does not double the late fee.