Oriole Medical manufactures hospital beds and other institutional furniture. The company's comparative balance sheet and income statement for 2019 and 2020 follow. Oriole Medical Comparative Balance Sheet As of December 31 2020 2019 Assets Current assets Cash $393,000 $417,400 Accounts receivable, net 1,077,000 776,450 735,000 681,050 Inventory Other current assets 381,400 247,050 Total current assets 2,586,400 2,121,950 Property, plant, & equipment, net 8,639,160 8,440,060 Total assets $11,225,560 $10,562,010 Liabilities and Stockholders' Equity Current liabilities $3,165,000 $2,846,050 Long-term debt 3,702,600 3,892,700 Total liabilities 6,867,600 6,738,750 Preferred stock, $5 par value 58,950 58,950 Common stock, $0.25 par value 104,650 103,850 4,194,360 3,660,460 Retained earnings Total stockholders' equity 4,357,960 3,823,260 Total liabilities and stockholders' equity $11,225,560 $10,562,010 Oriole Medical Comparative Income Statement and Statement of Retained Earnings For the Year 2020 2019 Sales revenue (all on account) $10,177,300 $9,613,950 Cost of goods sold 5,612,800 5,298,800 Gross profit 4,564,500 4,315,150 Operating expenses 2,840,200 2,634,150 Net operating income 1,724,300 1,681,000 Interest expense 300,300 308,700 Net income before taxes 1,424,000 1,372,300 Income taxes (30%) 427,200 411,690 Net income $996,800 $960,610 Dividends paid Preferred dividends 29,550 29,550 Common dividends 433,350 413,000 Total dividends paid 462,900 442,550 Net income retained 533,900 518,060 Retained earnings, beginning of year 3,660,460 3,142,400 Retained earnings, end of year $4,194,360 $3,660,460 Calculate the following profitability ratios for 2020. (Round answers to 1 decimal place, e.g. 50.1%.) a. Gross margin percentage 44.85 % b. Return on assets 11.1 % 15.6 % C. Return on common stockholders' equity