4) Al only consumes two goods, food (x1) and clothes (X2). Suppose that at an income of $1,000 he consumes 20 units of 11 and 50 units 01-11. When his income increases to $1,100, he consumes 15 units of x] and spends the rest of his money on 1;. There is no change in the price of the goods. a) What is Al's income elasticity for food (11)? b) What type of good are clothes (normal, neutral, or inferior}? How do you know