Pointing to a boy,Seema said,"He is the son of my grandfather's only child". How is the boy related to Seema?

Pointing to a man in a photograph,a woman said,"His brother's father is the only son of my grandfather." How is the woman related to the man in the photograph?

$A + B$ 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 $P \times R + Q$ mean?

$R$ is the daughter of $Q$. $M$ is the sister of $B$,who is the son of $Q$. How is $M$ related to $R$?

$A$ is the father of $C$. But $C$ is not his son. $E$ is the daughter of $C$. $F$ is the spouse of $A$. $B$ is the brother of $C$. $D$ is the son of $B$. $G$ is the spouse of $B$. $H$ is the father of $G$. Who is the grandmother of $D$?

$A$ family consists of six members $P, Q, R, S, T,$ and $U.$ There are two married couples. $Q$ is a doctor and the father of $T.$ $U$ is the grandfather of $R$ and is a contractor. $S$ is the grandmother of $T$ and is a housewife. There is one doctor,one contractor,one nurse,one housewife,and two students in the family. Who is the sister of $T?$