I'm pretty certain villain has 77 here, but i don't see how you can fold.
You can fold if you are 'pretty certain', if 'pretty certain' means you are going to be right at least 75% of the time (i.e. odds you are getting from the pot).
However, even given the strength of the move made by this guy, I'm not sure you can say he will have 77 (or 55, or 64) that often.
BTW, welcome to Blonde, Birts.