Please Help Fast

1. Cross one parent that is heterozygous for both beak color and feather color with a parent that is homozygous for both recessive traits. What are the genotypes of the parents? (Hint: Recall that the P generation includes a heterozygous parent with dominant traits and a homozygous parent with recessive traits.)
Assume the following F1 generation:
YyBb: 420
Yybb: 80
yyBb: 80
yybb: 420