Mendelian Genetics, Punnet squares

You cross an aa bb mutant plant with an AA BB wild type. What would the F2 segregation ratio be (wild type to mutant) if:

a.) both mutations, a and b, were recessive?
b.) both mutations were dominant?
c.) one mutation was dominant and one recessive?

(assume both mutations are required for the mutant phenotype)
(assume the genes are not linked)