|Falgor Finney, NPC|
"Move them tables boys and lets get some bets. Bare chest, no armor, and don't those of you with wiggle fingers get tryin' try to influence the action." He eyeballs a few folks he knows that would. "Even money bet this be." With that the bar springs into action and coin is exchanged as two "bookies' work the room and write out bettors.
As a default I'm going to assume the PCs place at least 10GP (up to a 50gp top bet) on Marcus.
Rex: 1d20 + 2 ⇒ (5) + 2 = 7
marcus: 1d20 + 3 ⇒ (15) + 3 = 18
*Assume the center table have been moved. You begin 10 feet away from one another. I'll update the map when I get home, if it's not concluded already.