Calculate the change in ph when hcl is added to a buffer solutio that is nh3 and nh4

1.) Calculate the change in pH when 4.00 ml of 0.100 M HCl (aq) is added to 0.100 mL of a buffer solution that is 0.100 M in NH3 (aq) and 0.1000 M in NH4Cl (aq).

2.) Calculate the change in pH when 4.00 mL of 0.100 M in NaOH (aq) is added to the original buffer solution.