Determine the amount of producer surplus generated in each of the following situations.
a. Gordon lists his old Lionel electric trains on eBay. He sets a minimum acceptable price, known as his reserve price, of $\$ 75 .$ After five days of bidding, the final high bid is exactly $\$ 75 .$ He accepts the bid.
b. So-Hee advertises her car for sale in the used-car section of the student newspaper for $\$ 2,000,$ but she is willing to sell the car for any price higher than $\$ 1,500 .$ The best offer she gets is $\$ 1,200,$ which she declines.
c. Sanjay likes his job so much that he would be willing to do it for free. However, his annual salary is $\$ 80,000$