The Central Division of National Inc. has operating income of $16,900 on sales revenue of $159,000. Divisional operating assets are $81,300, and management of National has determined that a minimum return of 13% should be expected from all investments. Required: a. Using the DuPont model, cakculate the Central Division's margin, turnover, and ROI (Do not round intermediate calculations. Round your answers to 2 decimol places.) b. Calculate the Central Divisioris residual income