Pointing to a person,a man said to a woman,"His mother is the only daughter of your father." How was the woman related to the person?

$P$ is the son of $Q$,while $Q$ and $R$ are sisters. $T$ is the mother of $R$. If $S$ is the son of $T$,which of the following statements is correct?

$A$ is the son of $B$; $C$,$B$'s sister,has a son $D$ and a daughter $E$; $F$ is the maternal uncle of $D$. How many nephews does $F$ have?

Introducing a man,a woman said,"He is the only son of my mother's mother." How is the woman related to the man?

$A + B$ means $A$ is the daughter of $B$; $A \times B$ means $A$ is the son of $B$; and $A - B$ means $A$ is the wife of $B$. If $Z \times T - S \times U + P$,what is $U$ to $Z$?

$D$ is $A's$ son. $C$ is the mother of $P$ and wife of $D$. How is $A$ related to $C$?