just listen in this question you said that ki boy is the brown eyed boy and girl is a blue eyed women so they had three children one or two of them they were having brown eyes and one of them was having Blue Eyes as shown in this they have three children in which two were having brown eyes and one was having Blue Eyes I don't know the diagram I only explained it but you get it that if you as the probability of brown eyes one for the probabilities 2 by 3