Maximizing EV in a School Survey

[ctv1116]

So I was offered to do a survey for a psych student at our school (we get e-mails to do surveys for money often). In each given week, you are permitted to "bet" $1 to $5 on each of the 16 games, but the total you bet must be less than $40. If after the 6 weeks this survey runs, if you are negative, you don't lose any money, but if you are positive, they write a check for the amount you won.

Here's the interesting part: the spreads they give for each game is shaded 1.5-2 points from the standard Vegas/offshore lines.

Here are the lines they posted:

Sun 9/11/05
Ravens at Titans +5
Steelers at Texans +7.5
Jaguars at Colts -10.5
Lions at Bears +3.5
Vikings at Bengals -4.5
49ers at Eagles -14.5
Bills at Buccaneers -4
Patriots at Panthers +4.5
Falcons at Seahawks -2.5
Rams at Cardinals +1.5
Dolphins at Jets -7.5
Browns at Packers -8
Chargers at Broncos -4.5
Chiefs at Raiders +3
Saints at Giants -4.5
Redskins at Cowboys -7.5

So, clearly, you must be on all of the underdogs, but what would be the general strategy for spreading your bets around?