In watermelons, bitter fruit (B) is dominant over sweet fruit (b), and yellow spots (S) are dominant over no spots (s). The genes for the two characteristics assort independently. A homozygous plant that has bitter fruit and yellow spots is crossed with a homozygous plant that has sweet fruit and no spots. The F1are intercrossed to produce the F2.

a.) What will the phenotypic ratio be in the F2 generation?

b.) If an F1 plant is backcrossed with the bitter, yellow spotted parent what phenotypes and proportions are expected in the offspring?

c.) If an F1 plant is backcrossed with the sweet, nonspotted parent what phenotypes and proportions are expected in the offspring?

I have a very difficult time setting these problems up! How would I start this problem, what would be the first step?