Step two tells us to take this PH value and to find the PKA right above it, right below it, sum them up, divide them by two and find the average. So the PKA value right above this PH is basically 4.1. The PK value right below it is 3.1. So we take 4.1 and 3.1. So we have 4.1 plus 3.1. Divide that by two, and that gives us so we have 7.2 divided by two, and that gives us 3.6.