Hopefully, sports will again start up soon, but let's pretend that the Avalanche is playing Arizona. Colorado is -140 while Arizona is -110. $140 on Colorado would win $100 but a bet in Arizona would only win $110 because they have a lower chance of winning. The the spread between the two is $30. So assuming people bet an equal amount of money on the two teams, then the bookie would make $30 for every $250 that is wagered. Bmbets.com (among others) will tell you the average price of a team across many bookmakers (close to the true probability of winning). Anyway, the spread for the entire game is $30.. ~$15 from each team. So, if you bet on Colorado, the price you must get would need to be $15 more than what the true probability suggests. So, if BMbets says they deserve a price of -160 and you are being offered -140, you're being offered $20 which is obviously more than the $15 that you owe the bookie.
