The R group of lysine has an amino group that can be positively

Subject: BiochemistryThe question states: The R group of lysine has an amino group that can be positively charged or lose a proton to become neutral. The pKa of the amino group is 10.8. Determine the fraction of amino group that is protonated at pH = 9.8 and at pH = 11.8.Please explain I don’t really know what I am supposed to do with this.