In mice, coat color is determined by 2 epistatically interacting genes. Mice with genotype aa for the first gene are always albino; otherwise, they can produce melanin. If they produce melanin (have at least 1 A allele), then their coat color is determined by a second gene. In particular, if their genotype at this second locus is bb, then they are black. Otherwise, they are agouti (brown). For example, a mouse with genotype Aabb is black, but one with genotype aabb is albino; genotype AaBb produces an agouti mouse. What is the phenotypic ratio of the following cross: aaBb x Aabb?