Calculate the [OH-] and pH for each of the following solutions?

Question

a) 0.085 M NaF

b) 0.055 M Na2S (Ka of H2S = 9.5 x 10^-8) c) a mixture that is 0.45 M NaC2H3O2 and 0.055 M in Ba(C2H3O2)2