Responsibility Accounting: Investment Center: ROI Naples, Inc recorded operating data for its shoe division for the year. Sales $800,000 Contribution margin 200,000 Controllable fixed costs 90.000 Average total operating assets 400,000 How much is ROI for the year if management is able to identify a way to improve the contribution margin by $30,000, assuming fixed costs are held constant? 57.5% 35.0% 30.0% 27.5% 22.5% MIUM SOUND DLL