Need help with Henderson-Hasselbalch equation

Hello, hopefully someone can help me! So I have 71 ml of acetic acid with a concentration of 0.1 and 1.059 g of sodium acetate that were mixed together in a volume of 250 mL to form an acetate buffer. The buffer concentration was 0.08. I was able to find the pH of the buffer which is 5 (or 4.99 if you prefer). I was able to find the concentration of the conjugate base which is 0.0516 (when we do 1.059 g/82.0343 then the answer divided by 0.25 L) and the concentration of the weak acid which is 0.0284 (when we do 0.071 L x 0.1/ 0.25). Like I said the buffer concentration is 0.08, the pH found was 5 and the pKa is 4.74. Now we have to take 50 mL of the buffer and add to it 1 ml of [0.1] HCL. I need to find the pH after the addition of the strong acid but I don’t know how to do it. Can someone tell me by what should I start first?