P is the wife’s brother’s son (or simply Brother-in-law's son / Nephew) of T.
Let's decode the given expression ‘P + Q ÷ R – S × T’ from left to right:
1. P + Q: P is the son of Q. (P is Male → Generation -1)
2. Q ÷ R: Q is the father of R. (Q is Male, and P and R are siblings)
3. R – S: R is the brother of S. (R is Male; P, R, and S are all siblings with Q as their father)
4. S × T: S is the wife of T. (S is Female, which means T is a Male married to S)
## Conclusion
* P, R, and S are siblings (children of Q).
* S is a female who is married to T.
* Therefore, P is the brother of T's wife (S).
* Since the question asks how P is related to T: P is T's brother-in-law (specifically, his wife's brother).