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 $380,000 $417,500 Accounts receivable, net 1,023,000 776,400 Inventory 742,000 681,050 Other current assets 381,300 247,050 Total current assets 2,526,300 2,122,000 Property, plant, & equipment, net 8,703,820 8,439,965 Total assets $11,230,120 $10,561,965 Liabilities and Stockholders' Equity Current liabilities $3,169,000 $2,846,000 Long-term debt 3,702,700 3,892,600 Total liabilities 6,871,700 6,738,600 Preferred stock, $5 par value 58,950 58,950 Common stock, $0.25 par value 104,600 103,900 Retained earnings 4,194,870 3,660,515 Total stockholders' equity 4,358,420 3,823,365 Total liabilities and stockholders' equity $11,230,120 $10,561,965 Sandhill Medical Comparative Income Statement and Statement of Retained Earnings For the Year 2020 2019 Sales revenue (all on account) $10,177,300 $9,614,000 Cost of goods sold 5,612,000 5,298,700 Gross profit 4,565,300 4,315,300 Operating expenses 2,840,300 2,634,200 Net operating income 1,725,000 1,681,100 Interest expense 300,350 308,650 Net income before taxes 1,424,650 1,372,450 Income taxes (30%) 427,395 411,735 Net income $997,255 $960,715 Dividends paid Preferred dividends 29,500 29,500 Common dividends 433,450 413,050 Total dividends paid 462,950 442,550 Net income retained 534,355 518,165 Retained earnings, beginning of year 3,660,515 3,142,350 Retained earnings, end of year $4,194,870 $3,660,515 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 %