The thing is with betting 40 and hoping he folds - if he does fold then you probably had him beat anyway so that's a bad thing. In this scenario lets say he either has the ace or doesnt and presume all the money is going on the flop.

You bet and he has an ace he is going AI - you lose your bet say $40
you bet and he hasnt got an ace hes folding.
you lose $40 in one of these and get him to fold the worst hand in the other one. neither result is good.

What do you think about checking and calling/raising?
considering that most players will auto-bet when checked to in a reraised pot - especially somebody playing 50/30.
Also - your hand has showdown value.

I think that checking is the best option.