I was on Bodog today looking at some of the straight bets for college football and pro football.

Here is what I noticed:
20 to win 20 when it says EVEN
20 to win 19.05 when it says -105
20 to win 18.18 when it says nothing (-110)
20 to win 17.39 when it says -115
20 to win 16.67 when it says -120

You can calculate how much you can win by multiplying your bet * 100 and then dividing by the juice. In other words, if you bet $40 at -120 then the amount you can win is $40*100/120=$33.33