Quote Originally Posted by clvacva
but the 51 is when we called. I thought we make the equity calculation before we call.

I am confused.
OK, think about it this way...

I will be using the numbers 13, 39, and 52 for simplicity of math (nice and close to our numbers). So before the call, our decision is to call $13 to win $39. We only have to be right 25% of the time for this to be breakeven (we lose $13 three times and win $39 once; we're right 1 of 4 times). Therefore, we only need to win 25% of the time (our equity), DUCY?

Now, if we were to divide 13/39, we get 33%. However, by the reasoning above, we know that's wrong. Dividing 13/52 gives us the 25%; the denominator (52) is the final pot.