If P + Q means P is the father of Q, P - Q means P is the wife of Q, and P x Q means P is the brother of Q, what does A - B + C x D mean about A and D?
A is D's mother. A - B: A is B's wife. B + C: B is C's father. C x D: C is D's brother, so D is also B's child. Since A is B's wife, A is the mother of D.
Explain it simply
Coded relation questions are blood-relation puzzles written in symbols. Decode each symbol pair from left to right into plain English, draw the tiny family tree, and only then answer. Do not try to hold it all in your head; three short lines of notes prevent most errors.
Example
Question: + = father of, - = wife of, x = brother of. Decode A - B + C x D.
- A - B: A is the wife of B. (A female, B male, married.)
- B + C: B is the father of C.
- C x D: C is the brother of D. (C male; D's gender unknown.)
A (wife) = B (husband)
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C (male) , D- D is a sibling of C, so D is also B's child.
- A is B's wife, so A is D's mother.
Follow-up: how is D related to A? D is A's son or daughter; D's gender is not given, so the answer is "child".
What to say in the interview
"I translate each pair: A is B's wife, B is C's father, C is D's brother. So D is B's child too, and B's wife A is D's mother. D's own gender isn't given, so D is only A's child."
Common mistakes
- Assuming D is male because C is a brother.
- Reading symbols right to left.