[SSJ2Bouchard]

Ho my... I have been searching an answer to this specific question for a long time! So we'll take this straight draw on the flop example again.
Let say I'm being offered 3 to 1 (half sized-pot bet, 50 in a pot of 100) on the flop, so if I hit on the turn, I must do at least 100 more to get even on my draw, right?
If I miss my straight draw, and the villain bets half the pot again, (75 in 150 this time) giving me 3 to 1 in my pot odds again, if I decide to call, how much more will have to gain to get even with my 2 calls?
It is 100 for the first call then 150 for the second call for a total of 250 more or am I totally wrong here ?