Prints of Darkness, the local copy shop, will print books for you. The cost of printing each book is 10 cents (i.e., 0.1 dollars) per page, plus the cost of the cover. They charge 2 dollars for a paperback cover and 5 dollars for a hardcover.

Write a Racket function printing-cost that consumes two values: a number of pages n, and a Boolean hardcover?, and produces the total cost in dollars of printing a book with the given number of pages with the given cover type.