I'm about to prove how ignorant I am when it comes to home improvement, but can you tell me how to determine the size of an extension ladder? I have an aluminum ladder in my garage that has been here for at least 20 years and never been touched so I would like to sell it. From the bottom rung to the top rung of each section, it measures 169" or a little over 14'. Does that make it a 28' ladder or is some deducted for the overlap when they are put together? Thanks for helping out an old, ignorant lady. 