Problem:
Isabella's house has 3 bedrooms. Each bedroom is 12 feet long, 10 feet wide, and 8 feet high. Isabella must paint the walls of all the bedrooms. Doorways and windows, which will not be painted, occupy 60 square feet in each bedroom. How many square feet of walls must be painted?
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Solution:
The perimeter of each bedroom is feet, so the surface to be painted in each bedroom has an area of square feet. Since there are 3 bedrooms, Isabella must paint square feet.
The problems on this page are the property of the MAA's American Mathematics Competitions