If 'K x L' means K is father of L, 'K+L' means K is wife of L and 'K-L' means K is brother of L, then what is the relation of N with P in 'M+N÷OxP'?

Let's decode the expression M+N÷OxP step-by-step using standard mapping (where $÷$ means sibling/brother link):
* $M+N⟹M$ is the wife of $N$ ($N$ is male).
* $N÷O⟹N$ is the brother of $O$.
* $O\times P⟹O$ is the father of $P$.

Since $N$ is the brother of $O$, and $O$ is the father of $P$, $N$ is the paternal uncle of $P$.