Temple University: Gerardo Mendoza and Dan Reich's "Calculus on the Web"
Click the "Index" button for Book II. Scroll down to "2. Applications of Integration," and click button 115 (Area between Curves I). Work on problems 6-13. Next, choose button 116 (Area between Curves II), and complete problems 4-10. If at any time a problem set seems too easy for you, feel free to move on.