Genes a and b are 20 cM apart. An a+b+/a+b+ individual was mated with an ab/ab individual.

a.) diagram the cross and show the gametes produced by each parent and the genotype of the F1.
b.) What gametes can the F1 produce, and in what proportions?
c.) If the F1 was crossed to ab/ab individuals, what offspring would be expected, and in what proportions?
d.) is this an example of the coupling or repulsion linkage phase?
e.) If the F1 were intercrossed, what offspring would be expected andin what proportions? I’m super lost on how to find the proportions.