You won a free ticket to see a Bruce Springsteen concert ( assuming the ticket has no resale value) U2 has a concert the same night, and this represents you next best alternative activity. Tickets to the U2 concert cost $80, and on any particular day, you would be willing to pay up to $100 to see this band. Assume that there are no additional cost of seeing either show. Base on the information, what is the opportunity cost of seeing Bruce Springsteen?