Encoded relations: Determine when M is the maternal uncle of N. Codes: A * B ⇒ A is the sister of B. A $ B ⇒ B is the mother of A. A + B ⇒ A is the brother of B. A = B ⇒ B is the father of A. Choose the expression that guarantees “M is the mother’s brother (maternal uncle) of N”.

Decode each segment

• N * P: N is the sister of P ⇒ N and P are siblings.
• P $ Q: Q is the mother of P.
• Q * M: Q is the sister of M ⇒ M is Q's brother (male).

Link to N
Since N and P are siblings and Q is P's mother, Q is also N's mother.M is Q's brother ⇒ M is the brother of N's mother ⇒ maternal uncle of N.

Why others fail

• M = P + Q * N: Q becomes N's sister, not mother.
• N + P = Q * M: Implies Q is both father (via “=”) and sister (via “*”), a gender contradiction.