Required: a. Prepare a vertical analysis of the two income statements. Round percentages to one decimal place. b. Use the vertical analysis to explain the increase in operating income. The vertical analysis indicates that the mix of revenues from Year 1 to Year 2. Product sales , while service sales in total revenues. Operating expenses slightly in total revenues with the result that operating income in total revenues. Of the operating expenses, marketing in total revenues, which might be related to the change in the mix of revenues. The other operating expenses . Overall, the change in the mix of revenues to affect operating income. Analyze Amazon.com Amazon.com, Inc. (AMZN) is the largest Internet retailer in the United States. Amazon's income statements through operating income for two recent years are as follows (in millions)