In coded relation type questions, the relationships are represented by certain codes or symbols such as + , - , ÷ , × , * etc. Then relationships between certain persons, given in the form of these codes, are to be analysed.
A + B means A is the son of B;
A - B means A is the wife of B;
A x B means A is the brother of B;
A ÷ B means A is the mother of B; and
A = B means A is the sister of B.
What does P = R + Q mean ?
P = R + Q means P is the sister of R who is the son of Q i.e. P is the daughter of Q.
So, the answer is (b).