The question is not really math, it is more statistics.

I think the problem is that you have not explained the problem you want to solve well enough.

The setup is a little unclear, are you flipping the coin 2 times.
I assume you have to the option before the flip.

First flip is fairly simple (if I have understood it correct), you can pick heads or tail.

Then is it unclear:

second one between #3 (tails) and whichever option that was picked in the first flip (heads).

You need to elaborate this....... ... ....