It is known that the hemophilia gene (blood incoagulability) is a recessive gene located on the X chromosome.

It is known that the hemophilia gene (blood incoagulability) is a recessive gene located on the X chromosome. A healthy woman, whose mother was just like her, was healthy, and whose father was hemophiliac, married a man with hemophilia. What offspring can be expected from this marriage (in relation to the disease in question)?

Given:
A-healthy
a-hemophilia
♂️XaY
Find: F1:
Decision:
Because it is known that the girl’s mother is healthy, which means her genotype is XAXA, and the girl’s father suffered from hemophilia, then his genotype is XaY, then the genotype of Levushka XaXa, i.e. she is the carrier of this trait and will pass it on to her offspring.
It is known that she married a man with hemophilia, which means their offspring:
R: ♀️XaXa * ♂️XaY
G: Xa Xa * Xa Y

F1: XAXa (healthy girl) 25%
XAY (healthy boy) 25%
XaXa (sick girl) 25%
XaY (sick boy) 25%