Even though I am not a chemistry major and have taken only general chemsitry, these are the some of the easiest problem realted to pH. Sove it using the :Henderson–Hasselbalch equation.
If you don't know that that is: http://en.wikipedia.org/wiki/Henderson%E2%80%93Hasselbalch_equation
pH is given, ka is given, calculate pka and slove for the ratio of base/acid.