Determine the expected phenotypes and genotypes | Homework Help

In parakeets, two genes control feather color. One of the genes determines whether a yellow pigment is made, and the other determines whether a blue pigment is made. If both the yellow and blue pigments are produced, the feather color is green. If no pigment is made, the feathers are white. The relevant genotypes:
Y_ B_ = green
Y_ bb = yellow
yy B_ = blue
yy bb = white
a. A white parakeet is crossed with a true-breeding yellow parakeet. What are the expected phenotypes and genotypes of the F1?
b. A male yellow parakeet from the F1 is crossed with a true-breeding female yellow parakeet. What are the expected phenotypes and genotypes from this cross?
c. To your surprise, the results of the cross in part “b” are as follows:
50% males, all of whom are yellow
50% females, half of whom are yellow and half of whom are white