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. So this is our pi, the isoelectric point for this particular tripeptide. So let's move on to example number two. So, once again, let's begin by drawing our peptide.