4. Sarah has $20 to spend on slices of pizza and cans of diet cola. Pizza costs $1 per slice, and diet cola costs $.50 per can.

a. Graph Sarah’s budget line for pizza and diet cola.

b. Suppose Sarah’s total budget for pizza and diet cola increases to $25. How does her budget line shift?

c. Draw a set of indifference curves for the situation in which pizza is a normal good, and one for the situation in which pizza is an inferior good.