9. a 10 percent increase in income brings about a 15 percent decrease in the demand for instant soup. what is the income elasticity of demand for instant soup? 10. given your previous answer, is instant soup a normal good or an inferior good? 11. calculate the cross-price elasticity of demand for products coffee and tea with the following information: when the price of coffee is $1.40, the quantity sold of tea is 80 cups; when the price of coffee is raised to $1.80, then 120 cups of tea are sold. 12. assume the quantity demanded of strawberry jam fell by 2% when the price of peanut butter rose 10%. calculate the cross-price elasticity of demand between tea and coffee. 13. given your previous answer, are strawberry jam and peanut butter complements or substitutes? 14. a 10 percent increase in the price of cheeseburgers at a local lunch shop would cause a 5 percent drop in total revenue from cheeseburgers and a 10 percent