please answer question b. and d.

4. Problem 4 - 14 Marks a. Write the formula for the cross-elasticity of demand. 3 Marks b. Suppose that the cross-price elasticity of demand between hot dogs and mustard is -1.50. If the price of hot dogs increase by 40%, by how much will the quantity demand of mustard increase or decrease 4 Marks c. Write the formula for the income elasticity of demand. 3 Marks d. Ann's income elasticity of demand for hockey tickets is 2.0. If her income increase by 20 percent this year, and she bought 12 tickets last year how many tickets will she likely buy this year, all other things being equal. 4 Marks