What a party! By midnight, you had at least fifty friends (or friends of friends) at your house, and people are going to be talking about your "Sweet 16th" forever--the music, the food, even the dancing. A good time was had by all, and your guests were generous with their gifts as well. Most of your friends handed you a five or ten dollar bill as they came in the door, and some of them even put the money inside a card!

However, the gifts weren't the only things left behind. The house is a total wreck--especially the living room. Your parents agreed to let you throw a party if you cleaned up any mess, and vacuuming alone isn't going to get that living room carpet clean. Looks like you're going to have to use some of that birthday money to pay for carpet cleaning.

Fortunately, today's paper is full of ads for professional carpet cleaning. Spotless Carpet Cleaners charges just $1.79 per square foot! SteamClean, on the other hand, charges $149 per room. Spotless sounds like the better deal, but how can you be sure?

If you remember what you learned in geometry class this year, you can figure out precisely how much you would have to pay each company, before taxes. Your living room carpet probably forms a rectangle or some other kind of quadrilateral. First, figure out the area of the quadrilateral (how many square feet). Then, you can multiply that number by the first company's rate per square foot and compare that price to SteamClean's rate per room.