The average price of a gallon of gas in 2015 dropped $0.94 (28 percent) from $3.34 in 2014 (to $2.40 in 2015). Required: 1. Conduct a horizontal analysis by calculating the year-over-year changes in each line item, expressed in dollars and in percentages for the income statement of Chevron Corporation for the year ended December 31, 2015 (amounts in billions). 2-a. Conduct a vertical analysis by expressing each line as a percentage of total revenues. 2-b. Excluding income tax and other operating costs, did Chevron earn more profit per dollar of revenue in 2015 compared to 2014