A rectangular piece of land to be developed as a memorial park has an area of . The length of the lot is three times the width of the lot. A rectangular path whose width is meters is to be constructed along the inner perimeter of the lot. The land contained within the path will be landscaped. The cost to construct the path is per square meter and the cost to landscape the inner field is per square meter. Express the total cost to develop this lot as a function of , the width of the path.