A man whose father was colour blind marries a woman who had a colour blind mother and normal father. What percentage of male children of this couple will be colour blind?

Here, the woman is a carrier as her mother is colourblind and father is normal.Father - XY                         Mother - XXcOffspring; XXc  - carrier daughter XX - Normal daughter XY- Normal son  XcY-Colorblind son50% sons are colorblind.