Part three: Calculation questions ( 30 points) 1. There are three industrial firms in Happy Valley. The government wants to reduce pollution to 90 units, so it gives each firm 30 tradable pollution permits. (1) Who sells permits and how many do they sell? Who buys permits and how many do they buy? Briefly explain why the sellers and buyers are each willing to do so. What is the total cost of pollution reduction in this situation? ( 8 points) (2) How much higher would the costs of pollution reduction be if the permits could not be traded? (7 points)