$A + B$ 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?

$A$ girl introduced a boy as the son of the daughter of the father of her uncle. The boy is the girl's:

$X$ introduces $Y$ saying,"He is the husband of the granddaughter of the father of my father." How is $Y$ related to $X$?

There is a family of six persons $A, B, C, D, E$ and $F$. They are Lawyer,Doctor,Teacher,Salesman,Engineer and Accountant. There are two married couples in the family. $D$,the Salesman,is married to the Lady Teacher. The Doctor is married to the Lawyer. $F$,the Accountant,is the son of $B$ and brother of $E$. $C$,the Lawyer,is the daughter-in-law of $A$. $E$ is the unmarried Engineer. $A$ is the grandmother of $F$. What is the profession of $A$?

$P$ is the brother of $Q$ and $R$. $S$ is $R$'s mother. $T$ is $P$'s father. Which of the following statements cannot be definitely true?

If $A + B$ means $A$ is the son of $B$,$A - B$ means $A$ is the husband of $B$,and $A \times B$ means $A$ is the sister of $B$,then which of the following shows the relation $Q$ is the maternal uncle of $P$?