Tarpaper Cabin Roof

Mark and his dad built a cabin 35 miles away from home. They couldn't afford steel roofing, and knew that a roof covered with blue tarps will not last over two years. They had enough money for the steel, but the freight was too much. His dad said that a good foundation and a good roof are the most important parts of a building. They decided to cover the cabin with tarpaper. Mark called a building supply place and found that they could use 15 lb tarpaper that has four squares in a roll, or they could use 90 lb paper that has 1 square in a roll. Mark hung up the phone and asked his dad ìHow much is a square?" His dad told him a square is 100 square feet: 10'x10' or 5'x20' or some combination that equals 100 when multiplied. Remember Area = Length x Width, or A=LW. 
How many square feet are in a roll of 90 lb paper?
How many squre feet are in a roll of 15 lb paper?They measured the roof. The roof was 20' long and the rafters were 12'.
Find the area of one side of the roof.
Double that to find the area of the whole roof.
How many squares is that?How many rolls of 15 lb paper will cover the roof? Round up to the nearest whole roll.
How many rolls of 90 lb. paper will cover the roof?If 15 lb paper costs $14 a roll, how much will it cost to cover the roof with 15 lb?
If 90 lb paper costs $36 a roll, how much will it cost to cover the roof with 90 lb?
Mark and his dad decided to use 90 lb paper even though it is much more expensive because his dad said it lasts much longer.
15 lb paper is better than a tarp, but still won't last more than 3 seasons, and they wouldn't be there to maintain the cabin all the time.
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