If ‘Z+Y’ means Z is the brother of Y, ‘Z÷Y’ means that Z is the father of Y…

Concept

In coded blood-relation puzzles, a multi-symbol expression is decoded strictly left to right, one operator (one direct relation) at a time. Two combination rules matter here: a sibling relation (brother/sister) carries a shared parent's relation unchanged to the sibling, since siblings have the same parents; and a sibling relation immediately followed by a parent relation, applied one generation down, produces an uncle/aunt link — the brother of someone's father is that person's uncle.

Application

Decode each coded chain the same way and track exactly how M ends up related to P:

1. M ÷ N × P + K: M is father of N; N is sister of P, so N and P share the same parents — which makes M the father of P directly, a one-generation-up relation, not an uncle relation.

2. M + S ÷ R ÷ P: M is brother of S; S is father of R; R is father of P. So S is grandfather of P, and M — S's brother — becomes P's grand-uncle: one generation too far to be simply 'uncle'.

3. M ÷ N + K × P: M is father of N; N is brother of K, so N and K share the same parents (making M father of K too); K is sister of P, so K and P also share the same parents — which again makes M the father of P directly.

4. M + K ÷ T × P: M is brother of K; K is father of T; T is sister of P, so T and P share the same parents — which makes K the father of P as well. M, being K's brother, is therefore the brother of P's father: exactly the definition of uncle.

Cross-check

Rebuilding the family tree behind 'M + K ÷ T × P' confirms it independently: K and M are siblings of the same generation; K is the father of both T and P, since T and P (linked by the sister code) share the same parents. That places M exactly one generation above P, as his father's brother, with no extra generation gap — matching the concept above and matching none of the other three chains, each of which either lands M as P's direct father or as a grand-uncle two generations up.