I'm trying to calculate basic EV for some classic heads-up situations, but I'm confused about something relatively simple. The basic equation for EV is:

EV=(% chance of winning)(amount won) - (% chance of losing)(amount lost).

Let's say I have AA and $100 in front of me. I manage to get all my money in PF against one opponent, who has a random hand. My % chance of winning is ~85% in this situation. Therefore, the equation should be:

EV=(85%)($X) - (15%)($100).

My problem is this: what value should I put in for $X? Is it just the $100 I expect to win off my opponent? Or is it the total pot amount, which would be $200? (I'm ignoring dead money, the blinds, and rake). I'm leaning towards the $200 value, but some info I've seen online suggests otherwise. Help!

Cheers,
Bug