Sandhill Medical manufactures hospital beds and other institutional furniture. The company's comparative balance sheet and income statement for 2019 and 2020 follow. Sandhill Medical Comparative Balance Sheet As of December 31 2020 2019 Assets Current assets Cash $376,000 $417,500 Accounts receivable, net 1,055,000 776,400 Inventory 731,000 681,050 Other current assets 381,400 247,050 Total current assets 2,543,400 2,122,000 Property, plant, & equipment, net 8,720,425 8,439,980 Total assets $11,263,825 $10,561,980 Liabilities and Stockholders' Equity Current liabilities $3,203,000 $2,846,100 Long-term debt 3,702,700 3,892,700 Total liabilities 6,905,700 6,738,800 Preferred stock, $5 par value 58,900 58,900 Common stock, $0.25 par value 104,600 103,800 Retained earnings 4,194,625 3,660,480 Total stockholders' equity 4,358,125 3,823,180 Total liabilities and stockholders' equity $11,263,825 $10,561,980 Sandhill Medical Comparative Income Statement and Statement of Retained Earnings For the Year 2020 2019 $10,177,200 $9,613,900 5,612,200 5,298,750 4,565,000 4,315,150 2,840,250 2,634,150 1,724,750 1,681,000 300,400 308,600 1,424,350 1,372,400 411,720 427,305 Sales revenue (all on account) Cost of goods sold Gross profit Operating expenses Net operating income Interest expense Net income before taxes Income taxes (30%) Net income Dividends paid Preferred dividends Common dividends Total dividends paid Net income retained Retained earnings, beginning of year Retained earnings, end of year $997,045 $960,680 29,550 29,550 433,400 413,050 462,950 442,600 534,145 518,080 3,660,480 3,142,400 $4,194,625 $3,660,480 Calculate the following profitability ratios for 2020. (Round answers to 1 decimal place, e.g. 50.1%.) % a. Gross margin percentage % b. Return on assets % C. Return on common stockholders' equity