Income statements for Thornton Company for Year 3 and Year 4 follow: THORNTON COMPANY Income Statements Year 4 Year 3 Sales $200,900 $180,900 Cost of goods sold 142,300 120,300 Selling expenses 20,800 18,800 Administrative expenses 12,300 14,300 Interest expense 3,500 5,500 Total expenses $178,900 $158,900 Income before taxes Income taxes expense Net income $ 15,500 $ 18,300 22,000 6,500 22,000 3,700 Required a. Perform a horizontal analysis, showing the percentage change in each income statement component between Year 3 and Year 4. b. Perform a vertical analysis, showing each income statement component as a percentage of sales for each year.