5. If a consumer's demand for a good moves in the same direction as the consumer's income, the consumer's demand for that good must be inversely related to the price of the good is called __________.
6. If the ___________ firm has zero costs or only has fixed cost, the quantity supplied in equilibrium is given by the point where the average revenue is zero.
8. If the ___________ firm has zero costs or only has fixed cost, the quantity supplied in equilibrium is given by the point where the marginal revenue is zero.