6. Suppose that a person regards ham and cheese as pure complements - he or she will always use one slice of ham in combination with one slice of cheese to make a ham and cheese sandwich. Suppoe also that ham and cheese are the only goods that this person buys and that bread is free. Show: (a) That if the price of ham is equal to the price of cheese, the own price elasticity of demand for ham is -0.5 and that the cross-price