Hi!
Let us assume that the following key:
Brown Body Color (Dominant) : B
Black Body Color (Recessive) : b
Red Eye Color (Dominant) : R
Brown Eye Color (Recessive) : r
To predict all possible phenotypes for this cross, you need to make a Punnet Square, which makes it easier to solve dihybrid crosses (crosses involving two different traits).
The concept of this is taking each combination of the traits from the parent (BR, Br, br, bR), and crossing it with such combinations of the other parent.
Refer to the attached picture for clarity.
This cross will yield a phenotypic ratio of
9 : 3 : 3 : 1
9 Dominant for both traits
3 Dominant for Eye Color, and Recessive for Body Color
3 Dominant for Body Color, and Recessive for Eye Color
1 Recessive for both traits
All Genotypes with Corresponding Phenotype:
BBRR - Brown Body, Red Eyes
BBrR - Brown Body, Red Eyes
BBRr - Brown Body, Red Eyes
bBRR - Brown Body, Red Eyes
BbRR - Brown Body, Red Eyes
BBrr - Brown Body, Brown Eyes
bBrR - Brown Body, Red Eyes
bBRr - Brown Body, Red Eyes
BbrR - Brown Body, Red Eyes
BbRr - Brown Body, Red Eyes
bBrr - Brown Body, Brown Eyes
Bbrr - Brown Body, Brown Eyes
bbRR - Black Body, Red Eyes
bbrR - Black Body, Red Eyes
bbRr - Black Body, Red Eyes
bbrr - Black Body, Brown Eyes
