chemistry - acids

Calculate The ph when 15cm3 of 0.1moldm-3 Naoh is added to 30cm3 of 0.600moldm-3 roanoic acid
Ka = 1.35 X 10 to the -5

Hi all I have tried to work this out and have got two ph's and would really appreciate someone responding to this asap with the answer

Just to clarify, did you mean propanoic acid as “roanoic acid” does not appear to exist.

I would suggest you show what you’ve tried so far: TSR is not a homework service and it is against the community guidelines to give answers and full solutions- it is preferred that you are given hints and guided towards getting a right answer.