Thank you for the opportunity to help you with your question!
38 are dominant, 42 are recessive.
Out of a population of 80, that's approximately 1/2 d and 1/2 r.
To be recessive, the genotype must be rr. We know one of the dominant alleles is d, but is the other one d or r?
If it were dd x rr, there wouldn't be any recessive at all. So it must be dr x rr. One half are phenotypically dominant and one half are phenotypically recessive; one half are heterozygous dominant, one half homozygous recessive.
Please let me know if you need any clarification. I'm always happy to answer your questions.