American odds can be basically interpreted as “The Net amount you win after making a $100 bet” So if the odds are +150 you win $150 PLUS your initial $100 bet if you win the bet.
Negative american odds means “the amount you have to be to win $100” so odds o −230 would mean you have to bet $230 to win $100
Yeah that’s fair, I’m just so used to American odds for gambling that I mentally use them all the time for these sorts of things.
Probably should have used good old fashioned odds instead.
The reason casino’s show something like “Yankee’s +110 Red sox −120” is so you can easily see the casino’s rake or something.