The following data are from the accounting records of Niles Castings for year 2. Units produced and sold 89,000 Total revenues and costs Sales revenue $340,000 Direct materials costs 65,000 Direct labor costs 35,000 Variable manufacturing overhead Fixed manufacturing overhead 15,000 42,000 Variable marketing and administrative costs Fixed marketing and administrative costs. 13,500 36,000 Required: a. Prepare a gross margin income statement. b. Prepare a contribution margin income statement.