Comparative Balance Sheet As of December 31 Assets Current assets Cash 20202019 Accounts receivable, net Inventory Other current assets Total current assets Property, plant, \& equipment, net Total assets Liabilities and Stockholders' Equity Matthias Medical Comparative Income Statement and Statement of Retained Earnings For the Year Sales revenue (all on account) Cost of goods sold Gross profit $10,177,200$9,613,900 Operating expenses Net operating income Interest expense Net income before taxes 4,765,4005,411,8004,315,2005,298,700 Income taxes (30%) Net income Dividends paid 1,865,5002,899,9001,681,1002,634,100 \begin{tabular}{lrr} Preferred dividends & 29,450 & 29,450 \\ Common dividends & 419,270 & 413,000 \\ \cline { 1 - 2 } & 448,720 & 442,450 \\ Total dividends paid & 646,920 & 518,300 \\ Net income retained & 3,660,600 & 3,142,300 \\ \cline { 2 } \cline { 4 } Retained earnings, beginning of year & $4,307,520 & $3,660,600 \end{tabular} Calculate the following profitability ratios for 2020 . (Round answers to 1 decimal ploce, eg. 50.1\%.) a. Gross margin percentage % b. Return on assets c. Return on common stockholders' equity %