X + Y means X is the mother of Y, X − Y means X is the brother of Y, X * Y means X is the sister of Y. Then what does A − B + C mean?

Correct — B.
Rule: translate each symbol, then chain the links through the middle person.

A − B: A is the brother of B.
B + C: B is the mother of C.

A is the brother of C's mother, so A is C's maternal uncle → option (b).

Why the others are wrong

• (a)
  A is brother-in-law of C — Brother-in-law means a spouse's brother or a sister's husband. A is neither to C. He is the brother of C's mother, one generation above C.
• (c)
  A is brother of C — Brother would put A in C's own generation. A is B's brother and B is C's mother, so A is a generation above C.
• (d)
  A is father of C — Father of C would be B's husband. The code makes A B's brother, and a mother's brother is an uncle, not a father.

Coded blood relations are solved by translating each symbol into one relation and chaining the links in order. A − B + C has two links: A to B (brother) and B to C (mother).

B joins the two links. A is B's sibling and B is C's parent, so A is C's parent's sibling, an uncle. Because B is the mother, it is the maternal side.

Key facts

• Mother's brother = maternal uncle. Father's brother = paternal uncle.
• A − B makes A male: he is B's brother.
• B + C makes B female: she is C's mother.

Common traps

• Stopping at the first link and choosing brother
• Choosing father because A is male and sits in the parent generation

No directly related past PYQ was found.