The boy is the son in law of the girl, in other words, The girl is the mother in law of the boy.
Pointing to a girl in photograph. Amar said, "Her mother's brother is the only son of my mothers's father." How the girl's mother related to Amar?
Pointing out to a lady, a girl said "She is the daughter-in-law of the grand mother of my father's only son" How is the lady related to the girl?
"Introducing a lady to her friend, Juliet said, 'Her father-in-law's father's only son's, only daughter's brother, is grandfather to my daughter.' How is the woman related to Juliet?
The Traffic police stops them at a signal.
He asks them How are they related.
So the boy answers : “Her father-in-law is my father-in-law’s father”
Question: How they are related?