3. (2 points) Currently, a firm's per unit cost of production is $15 per unit while its cost of producing an extra unit of output is $15.75. Is this firm experiencing increasing, decreasing, or constant returns to scale? Explain. 4. (2 points) Assuming that the supply of labor is the same for grocery clerks is the same as the supply curve for pizza delivery people, explain why pizza delivery people earn more per hour than grocery clerks. Assume there are no unions or monopsonies.