The hemophilia gene is located 12 map units from the red-green colorblindness gene on the X chromosome. Red-green colorblindness is recessive to normal colorvision. A woman with normal blood clotting and normal color vision, but whose father was a hemophiliac and whose mother was red-green colorblind, marries a man who is not a hemophiliac and is not colorblind. What percent of their children will be colorblind and have hemophilia?

The answer was given. It is 3%. But I need to know how to get that answer.