If merpeople have tail color alleles b (blue) and g (green) that follow the codominance inheritance rule, what are possible genotypes and phenotype?

Genotypes: BG.  Phenotypes:  The tails would express both, blue and green, colors.

Explanation:

The codominance inheritance rule states that both alleles for a single trait will dominate and will be equally expressed.  And, in this case, the alleles, B and G, for tail color will be equally expressed in their offspring.

Hope this helps!

c. establishing proper sleep hygiene