Problem 2-28 (Static) Understanding income statement relationships-Apple Incorporated LO 2-2, 2-4 Selected data from the September 26, 2020, and September 28, 2019, consolidated balance sheets and income statements (statements of operations) for the years then ended for Apple Incorporated follow. All amounts are reported in millions. Net sales Cost of sales Research and development expenses Selling, general, and administrative expenses Operating incone Other incone, net Provision for income taxes Net income Required: 2020 $274,515 2019 $260,174 169,559 10.752 19,916 161,782 16,217 18,245 7 7 1,007 9,680 $57,411 $55,256 a. Calculate the amount of Apple's gross profit for each year. Has gross profit as a percentage of sales changed significantly during the past year? b. Calculate the amount of Apple's operating income for each year. Has operating income as a percentage of sales changed significantly during the past year? c. After completing requirements a and b, calculate the other missing amounts for each year.