9. Three bidders have a private valuation for an item. Their valuations are 10, 15 and 20 for Bidders 1, 2 and 3 respectively. The auctioneer uses a second price sealed bid auction format. a) What is the equilibrium bidding strategy for each bidder? b) Consider Bidder 2's equilibrium bidding strategy. Show that no deviation fro this strategy would be profitable. c) Who wins the auction and what do they pay? d) How would the bids differ if a first price sealed bid format were used? (No calculation necessary.) e) If the bidders were to collude, could they all be made better off