Consider a discontinuous trait relating to the management of cholesterol in humans. Assume the trait is controlled by just 2 unlinked genes. For the cholesterol receptor gene 9 different alleles exist. For the cholesterol processing enzyme 5 distinct alleles exist. For the receptor gene how many different genotypes are possible?

Assume that for the trait both genes are required and each distinct genotype results in a distinct phenotype. How many different phenotypes are possible?