You can either use an ice table or the Henderson-Hasselbalch equation. I would use the Henderson-Hasselbalch equation since that is the easiest method to use in my opinion. The Henderson-Hasselbalch equation is pH=pKa+log([A⁻]/[HA]). pKa=-log(Ka) (which equals 1.77 in this question) [A⁻]=concentration of conjugate base (0.386M in this question) [HA]=concentration of acid (0.451M in this question) When you plug everything in you should get a pH of 1.697. I hope this helps. Let me know if anything is unclear or you want me to explain anything in more detail.
