TILE Mark is purchasing new tile for his bathrooms. The home improvement store charges $48 for each box of tiles when three or fewer boxes are purchased, $45 for each box when 4 to 8 boxes are purchased, $42 for each box when 9 to 19 boxes are purchased, and $38 for each box when more than nineteen boxes are purchased a. Write a piecewise-defined function describing the cost of the boxes of tile. b. What is the cost of purchasing 5 boxes of tile? What it is the cost of purchasing 19 boxes of tile?