So uppercase R, lowercase R, so we have the father and the mother and they have an offspring, a child. Now, what this describes is the probability of the child being RH positive or RH negative. So because the gene is dominant to the recessive trait that means upper case R and uppercase R will be RH positive. And so will uppercase R and lowercase R because uppercase R is dominant over lowercase R. So we have one, two, three out of four will be our RH positive. And so 75% will be RH positive. And there's a 25% chance that it will be RH negative.