The average price of a gallon of gas in 2018 increased $0.30 (12.4 percent) from $2.42 in 2017 to $2.72 in 2018 . 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 Combustion Petroleum for the year ended December 31, 2018 (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 Combustion earn more gross profit per dollar of revenue in 2018 compared to 2017? Complete this question by entering your answers in the tabs below. 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 Combustion Petroleum for the year ended December 31, 2018 (amounts in billions). (Decreases should be indicated by a minus sign. Enter your answers in billions (i.e., 10,000,000,000 should be entered as 10 ). Round percentage values to 1 decimal place.) The average price of a gallon of gas in 2018 increased $0.30 (12.4 percent) from $2.42 in 2017 to $2.72 in 2018 . 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 Combustion Petroleum for the year ended December 31, 2018 (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 Combustion earn more gross profit per dollar of revenue in 2018 compared to 2017? Complete this question by entering your answers in the tabs below. Conduct a vertical analysis by expressing each line as a percentage of total revenues. (Round percentage values to 1 decimal place.) The average price of a gallon of gas in 2018 increased $0.30 (12.4 percent) from $2.42 in 2017 to $2.72 in 2018 . 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 Combustion Petroleum for the year ended December 31, 2018 (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 Combustion earn more gross profit per dollar of revenue in 2018 compared to 2017? Complete this question by entering your answers in the tabs below. Excluding income tax and other operating costs, did Combustion earn more gross profit per dollar of revenue in 2018 compared to 2017