Pointing to a photograph,Sachin said,"She is the grandmother of my father's sister's son." How is the woman in the photograph related to Sachin?

Pointing to a photograph,a woman says,"This man's son's sister is my mother-in-law." How is the woman's husband related to the man in the photograph?

$A$ boy goes to see a film and finds a man who is his relative. The man is the husband of the sister of his mother. How is the man related to the boy?

$I. A, B, C, D, E$ and $F$ are six members of a family.
$II.$ One couple has parents and their children in the family.
$III. A$ is the son of $C$ and $E$ is the daughter of $A$.
$IV. D$ is the daughter of $F$ who is the mother of $E$.
What relationship do $D$ and $E$ bear to each other?

$A + B$ means $A$ is the son of $B$; $A - B$ means $A$ is the wife of $B$; $A \times B$ means $A$ is the brother of $B$; $A \div B$ means $A$ is the mother of $B$; and $A = B$ means $A$ is the sister of $B$.
What does $P + R - Q$ mean?

$A$ and $B$ are brothers,$C$ and $D$ are sisters. $A$'s son is $D$'s brother. How is $B$ related to $C$?