The following data are from the accounting records of Niles Castings for year 2 . Required: a. Prepare a gross margin income statement. b. Prepare a contribution margin income statement. Complete this question by entering your answers in the tabs below. Prepare a gross margin income statement. Required: a. Prepare a gross margin income statement. b. Prepare a contribution margin income statement. Complete this question by entering your answers in the tabs below. Prepare a gross margin income statement. Complete this question by entering your answers in the tabs below. Prepare a contribution margin income statement