Suppose that a dominant allele (P) codes for a polka-dot tail and a recessive allele (p) codes for a solid colored tail. In addition, suppose that a dominant allele (L) codes for long eyelashes and a recessive allele (l) codes for short eyelashes. If two individuals heterozygous for both traits (tail color and eyelash length) mate, the probability of the phenotypic combinations of the offspring are: PPLL (1/4); PpLl (1/2); ppll (1/4).

2 + 3 - 4 + (5 × 4)
=2 + 3 - 4 + 20
=5 - 4 + 20
=1 + 20
=21