Symbiosis National Aptitude Test SNAP 2019 Paper

A + B : A is sister of B.
A/B : A is son of B.
A = B : A is brother of B.
A @ B : A is father of B.
Now, P @ B = S @ M = N.
P is father of B, who is brother of S and S is father of M and M is brother of N.
(+) P - (+) B - S (+) = (+) M - N
Hence, M is grandson of P.