Ivanhoe Medical manufactures hospital beds and other institutional furniture. The company's comparative balance sheet and income statement for 2019 and 2020 follow. Ivanhoe Medical Comparative Balance Sheet As of December 31 2020 2019 Assets Current assets Cash $359,000 $417,450 Accounts receivable, net 1,014,000 776,400 Inventory 736,000 681,000 Other current assets 381,350 247,000 Total current assets 2,490,350 2,121,850 Property, plant, & equipment, net 8,737,045 8,439,895 Total assets $11,227,395 $10,561,745 Liabilities and Stockholders' Equity Current liabilities $3,167,000 $2,846,000 Long-term debt 3,702,600 3,892,600 Total liabilities 6,869,600 6,738,600 Preferred stock, $5 par value 58,950 58,950 Common stock, $0.25 par value 104,650 103,850 Retained earnings 4,194,195 3,660,345 Total stockholders' equity 4,357,795 3,823,145 Total liabilities and stockholders' equity $11,227,395 $10,561,745 Ivanhoe Medical Comparative Income Statement and Statement of Retained Earnings For the Year 2020 2019 Sales revenue (all on account) $10,177,200 $9,613,950 Cost of goods sold 5,612,550 5,298,800 Gross profit 4,564,650 4,315,150 Operating expenses 2,840,250 2,634,150 Net operating income 1,724,400 1,681,000 Interest expense 300,400 308,650 Net income before taxes 1,424,000 1,372,350 Income taxes (30%) 427,200 411,705 Net income $996,800 $960,645 Dividends paid Preferred dividends 29,500 29,500 Common dividends 433,450 413,100 Total dividends paid 462,950 442,600 Net income retained 533,850 518,045 Retained earnings, beginning of year 3,660,345 3,142,300 Retained earnings, end of year $4,194,195 $3,660,345 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