Hopefully, this is a question you will ask often because it means you’re winning. Most NFL games against the point spread are -110, which means you must wager $110 to win $100. That $10 difference is what is called “the vig’’ that’s the house’s advantage and among other things what keeps them in business. That’s also why they want the exact amount bet on each game.
For every $1,000 bet on each team they made $100. So multiply that by the thousands they take in every week and then by 16 games per week and you know why casinos can give you a free breakfast buffet. Back to the point, if you bet an equal amount on three games (say $110 to win $100) and you win two of three your profit for the day would be $90. The two wins would get you $200 minus the $110 for the loss.