0 mL sample of a 0.1900 M solution of aqueous trimethylamine is titrated with a 0.2375 M solution of HCl. Calculate the pH of the solution after 10.0...

A 25.0 mL sample of a 0.1900 M  solution of aqueous trimethylamine is titrated with a 0.2375 M  solution of HCl. Calculate the pH of the solution after 10.0 ml & 20.0 mL of acid have been added; pKb of (CH3)3N = 4.19 at 25°C.

For the 10.0 ml addition I got : pH=9.8

I just need help with the 20 mL part, Thanks.