Problem 9-20B Return on investment Bonner Corporation's balance sheet indicates that the company has $320,000 invested in operating assets. During Year 3, Bonner earned $24,000 of operating income on $480,000 of sales. Required a. Compute Bonner's operating profit margin percentage for Year 3. b. Compute Bonner's turnover for Year 3. c. Compute Bonner's return on investment for Year 3. d. Recompute Bonner's ROI under each of the following independent assumptions: (1) Sales increase from $480,000 to $560,000, thereby resulting in an increase in operating income from $24,000 to $28,000. (2) Sales remain constant, but Bonner reduces expenses, thereby resulting in an increase in income from $24,000 to $25,920. (3) Bonner is able to reduce its operating assets from $320,000 to $300,000 without affecting income