A buffer containing 0.2000 M of acid, HA, and 0.1500 M of its conjugate base

A buffer containing 0.2000 M of acid, HA, and 0.1500 M of its conjugate base, A-; has a pH of 3.35. What is the pH after 0.0015 mol NaOH is added to 0.500 L of this solution?