the wall is rectangular, so its area is simply the length * width, namely 42 * 25.5 = 1071 ft² in area.
since the cost is a total of 771.12 for the whole 1071 ft², how much is it for just 1 ft²?
we simply get the quotient from 771.12 ÷ 1071 = 0.72, namely 72 cents per each ft².
