Pointing to a man,a woman said,"His mother is the only daughter of my mother." How is the woman related to the man?

$A + B$ 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?

$A$ family consists of six members $P, Q, R, X, Y$ and $Z$. $Q$ is the son of $R$ but $R$ is not the mother of $Q$. $P$ and $R$ are a married couple. $Y$ is the brother of $R$. $X$ is the daughter of $P$. $Z$ is the brother of $P$.
How is $Q$ related to $X$?

$A$ woman introduces a man as the son of the brother of her mother. How is the man related to the woman?

$A$ woman walking with a boy meets another woman and on being asked about her relationship with the boy,she says,'My maternal uncle and his maternal uncle's maternal uncle are brothers'. How is the boy related to the woman?

Deepak is the brother of Ravi. Rekha is the sister of Atul. Ravi is the son of Rekha. How is Deepak related to Rekha?