Vaughn Manufacturing recorded operating data for its auto accessories division for the year. Sales $810000 Contribution margin 270000 Total direct fixed costs 90000 Average total operating assets 400000 How much is ROI for the year if management is able to identify a way to improve the contribution margin by $40000, assuming fixed costs are held constant? O 11.1% O 45.0% 55.0% O 77.5%