Betting on baseball

I know the season is over, but I was wondering how baseball odds work ie:

N.Y. Yankees -130 N.Y. Mets +120

Thanks!!

Those are the odds in a particular game.

In this case, if you bet on the Yankees $100 and they win, you get $100. If you lose, you have to pay $130. With the Mets, you win $120 if they win, and lose that $100 if you bet on them and they lose.


Yer pal,
Satan

*TIME ELAPSED SINCE I QUIT SMOKING:
Six months, two weeks, four days, 23 hours, 17 minutes and 44 seconds.
8078 cigarettes not smoked, saving $1,009.85.
Extra time with Drain Bead: 4 weeks, 1 hour, 10 minutes.

*THE YANKEES WIN! THAAAAAAH YANKEES WIN!
1996 · 1998 ··· WORLD CHAMPIONS ··· 1999 · 2000
26 Titles! The #1 Dynasty of all-time!
And most importantly… RULERS OF NYC!!