Darren bought a ticket to a football game at $504 and Joe bought a ticket to a concert at $685.Both events will be held at the same time and the tickets are nonrefundable.Joe finds the football game to be interesting and offers to directly swap tickets with Darren.Suppose that Darren values the game at $650 and the concert at $826.Darren's opportunity cost of rejecting Joe's offer and going to the football game is (answer) dollars.

What is the value of (answer)?