2 genes affecting one phenotype on X chromosome

Suppose that r, red, and sc, scarlet, are two recessive eye-color mutations that lie 20 map units apart on the Drosophila X chromosome, and that each causes a red eye color in place of the wild type purple color.

A. If a female from pure-breeding rr stock is mated with a red-eyed (sc) male, what phenotypes will the F1 sons and daughters display?

B. If these F1 flies are interbred, what will be that phenotypic ratios among the F2 granddaughters and grandsons?

I have trouble starting on this question.
I realize that the two genes are both on the X chromosome and I think the parental genotypes might be
r = red; s=scarlet
female: X^(r/S) X^(r/S); and male: X^(R/s) Y ?

Then in A. the F1 would be:
female: X^(r/S) X^(R/s); and male X^(r/S) Y
female: purple eyed; and male: red-eyed

I'm not sure whether that's correct and when the map units come into play, nor how to do part B.

Would be great if someone could guide me in the right direction here, thank you!