Mukesh said to his friend, "Rita is the mother of my son's wife'daughter". How is Mukesh related to Rita?

Explanation

"My son’s wife’s daughter" = daughter of the daughter-in-law = Mukesh’s granddaughter. "The mother of that daughter" = daughter-in-law. That means Rita is Mukesh’s daughter-in-law. When a woman is the wife (daughter-in-law) of a man’s son, then that man is the father-in-law of that woman.