Blood relations with symbolic operators: Identify the expression that makes Q the grandmother of T. Operator meanings: A + B ⇒ B is the brother of A A x B ⇒ B is the husband of A A - B ⇒ A is the mother of B A % B ⇒ A is the father of B Choose the expression that shows "Q is the grandmother of T".

Interpret each operator carefully

• A + B ⇒ B is brother of A (second person male, sibling).
• A x B ⇒ B is husband of A (second person male, spouse).
• A - B ⇒ A is mother of B (first person female, parent).
• A % B ⇒ A is father of B (first person male, parent).

Check option (a): Q - P + R % T
Q - P ⇒ Q is mother of P. P + R ⇒ R is brother of P (so Q is also R's mother). R % T ⇒ R is father of T ⇒ T is grandchild of Q. Thus Q is grandmother of T.

Why others fail
(b) and (d) make Q the grandfather, not grandmother; (c) never links T as a descendant of Q.