So first we have to figure out the area of the smaller wall. We know it is 10 feet high and 20 feet long, so we multiply the length and width together to get 200 square feet, and that equals 1 ton. Now if we take the 1800 square foot wall and divide it by the smaller wall, we get 9. This is because the larger wall is 9 times the size of the smaller wall. So if the smaller wall needs 1 ton, and the larger would need 9 times the amount, we would need 9 tons.
