How do I file taxes for online arbitrage betting? Do I need to record winnings/losses for each transaction or only the gain from a given session?

Example: I bet 100 on Team A at one place and 100 on Team B at another. Either way the payout is 210. Profit from session = 210-200. Say Team A won. Do I report 110 in winnings (from the bet on A) and itemize 100 in losses (from the bet on B)? Or just the 10$ won from the entire session?