Please help with this revenue and profit maximization Calculus problem.

Demand for the latest best selling book is given by q= -p^2 + 33p + 9 (18< or equal to p < or equal to 28) copies sold per week when the price is p dollars. Can you help me determine what price to charge to obtain the largest revenue? It costs C= 9q+100 dollars to sell q copies of this book in a week. What price should the company charge to get the largest weekly profit? What is the maximum weekly profit and how can you be sure that the profit is maximized?

Must use calculus.

Thank you