Concept:
Decode the symbols one by one from left to right.
Step 1: Interpret each relation.
Given:
\[
P \div Q + R - S \times T
\]
From rules:
\[
P \div Q
\]
means:
\[
P \text{ is father of } Q
\]
\[
Q + R
\]
means:
\[
Q \text{ is brother of } R
\]
So Q and R are siblings.
\[
R - S
\]
means:
\[
R \text{ is mother of } S
\]
\[
S \times T
\]
means:
\[
S \text{ is sister of } T
\]
So S and T are siblings.
Step 2: Build the family tree.
Since Q and R are siblings, and P is father of Q:
\[
P \text{ is also parent generation of } R
\]
R is mother of S.
S is sister of T.
So T is also child of R.
Thus:
\[
P \to R \to T
\]
This means:
P is father of R, and R is parent of T.
Hence:
\[
P \text{ is grandfather of } T
\]
Thus, the required answer is:
\[
\boxed{\text{Grand father}}
\]