In a certain code language, 'E + F' denotes 'E is the brother of F', 'E - F' denotes 'E is the sister of F', and 'E × F' denotes 'E is the father of F'. If P × Q - R + S, then how is R related to P?

Pankaj (Male) pointed to a girl and said, 'Her paternal grandfather's only son's wife is my mother.' What is Pankaj's relation to that girl?

A + B means 'A is the wife of B'; A - B means 'B is the daughter of A'; A × B means 'B is the brother of A'; A ÷ B means 'A is the father of B'. If P + R × T - Q + S ÷ U, then how is P related to the mother of U?