The simple way of doing pot odds:

You have 36bb in the pot, and he has his full stack stack. Add the two for the pot size, and ignoring the blinds you have a 136bb pot. You have to call the rest of your stack, which is 64bb.

So to get your pot odds just devide the pot size (136) by what you have to call (64)

136/36 = 2.1, so youre getting 2.1:1