Selected data from the September 30, 2017, and September 24, 2016, consolidated balance sheets and income statements for the years then ended for Apple Inc. follow. All amounts are reported in millions. 2017 2016 Net sales $229, 234 $215, 639 Cost of sales 141, 048 131, 376 Research and development expenses 11, 581 10, 045 Selling, general, and administrative expenses 15, 261 14 , 194 Operating income ? ? Other income, net 1, 348 Provision for income taxes 15, 738 Net income $ 48, 351 $ 45, 687 Required: 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. Indicate the financial statement effect