And then, if we bring this side to the left, this denominator to the left side, we get the following equality. So, we see that when the PH is equal to the PKA, when the PH of our solution inside the cell is equal to 9.7. So, somewhere about here, we see that the concentration of the ha is equal to the concentration of the a. Now, what is ha in this case? Well, H A we said is the guanine. And our a is basically this deproynated guanine.