2. (VCG for Position Auctions) Suppose that there are 3 ad slots on the Google search page. The top slot gets 100 clicks per hour, the middle slot gets 50 clicks per hour, and the bottom slot gets 20 clicks per hour. There are 4 advertisers interested in the ad slots. Google implements the VCG mechanism to sell these slots and asks the advertisers to submit their bids for the amount of money they are willing to pay per click.

Suppose that advertisers 1, 2 and 3 submit the bids $10 per click, $5 per click, $4 per click and $2 per click. How much will each advertiser pay at the end of one hour? How about under GSP?