Question: In Martian squirrels, a dark tail (D) is dominant to a clear tail (d) and a short tail (S) is dom…

In Martian squirrels, a dark tail (D) is dominant to a clear
tail (d) and a short tail (S) is dominant to a long tail (s). The
genes are linked. In a cross between one homozygous recessive
parent and another whose genotype is DS/ds, the following progeny
result: -2198 dark short -2219 clear long -68 dark long, and -75
clear short. What is the recombination frequency between the
tail-length and tail- color genes?