If you're unsure about your bet you can go for the middle and bet +10 on Minny now. Some people do this to hedge their bets and the worse case scenario is you lose the juice. If you're lucky and win both sides (GB - 7.5 and MInny +10) and then Greenbay wins by say 8 or 9 points, then you got two winners.
Basically, if you took Minny now, it would be a low risk but potentially high reward bet. The downside is you probably will lose 10 percent of one bet (given -110 odds) but that's not too bad if you're re thinking betting on GB and there is always the chance that you get the middle right.