Color-blindness is a sex-linked recessive trait. A color-blind mom and a color-seeing dad have children. In the Punnett square, the R represents the dominant allele of seeing color and the r represents the recessive allele of color-blindness.
The answer should be 50% assuming that the dad has one recessive trait. If the dad has no recessive trait then it would be 0%. but most likely its 50%.
