Maria purchases two goods, food and clothing. She has a diminishing marginal rate of substitution of food for clothing. Let x denote the amount of food consumed and y the amount of clothing. Suppose the price of food decreases from Px1 to Px2. On a clearly labeled graph, illustrate the income and substitution effects of the price change on the consumption of food. Do so for each of the following cases:

a) Case 1: Food is a normal good.

b) Case 2: The income elasticity of demand for food is zero.