If J + K means J is the brother of K, J × K means J is the mother of K, and J…

In these coded relation puzzles, the operators are fixed: '+' = brother, '×' = mother, and '/' = sister, always read as "first person [operator] second person". An uncle of a person X is the brother of one of X's parents — so, structurally, the coded statement for "P is the uncle of X" must be a two-step chain of exactly this shape: P + Y (P is the brother of some connecting person Y) followed by Y × X (Y is the mother of X), sharing the same middle person Y. Any other operator order or combination encodes a different relationship — direct sibling, direct parent, or something else — not an uncle.

Each option chains two relations through a shared middle letter — read left to right, evaluate the first operator between the first two letters, then the second operator between the last two letters.

1. C / D + A: the first relation, C / D, already states C is the sister of D — a direct sibling relation to D.

2. C × D + A: the first relation, C × D, already states C is the mother of D — a direct parent relation to D.

3. C × A + D: the first relation, C × A, states C is the mother of A; the second, A + D, states A is the brother of D, so A and D are siblings — making C a parent of D as well.

4. C + A × D: the first relation, C + A, states C is the brother of A; the second, A × D, states A is the mother of D — so C is the brother of D's mother.

Only the chain C + A × D matches the required brother-then-mother pattern through the same connecting person, and the genders stay consistent throughout (C stays male via '+', matching 'uncle').

Contrast:

• C / D + A makes C a sibling of D, not the brother of D's parent.

• C × D + A makes C the parent of D directly, not the parent's brother.

• C × A + D makes C a parent of D (via the shared sibling A), not the sibling of D's parent.

Therefore, the expression C + A × D is the one that correctly states C is the uncle of D.