You have a free ticket to see Lady Gaga in concert, this ticket having no resale value. Pink is performing on the same night, which is your second-best alternative. The Pink ticket costs $180, and on any given day you would be willing to pay up to $190 to see Pink.
Assume there are no other costs of seeing either performer.
a. Assuming you could not get the Pink ticket for free what is your opportunity cost of your seeing Lady Gaga?