In the code, if P - Q means P is the father of Q, P + Q means P is the son of Q, and P ÷ Q means P is the sister of Q, what is the relation of R if P - Q ÷ R?
In a coded relationship, if A + B means A is the father of B, A - B means A is the daughter of B, and A × B means A is the son of B, what is the relationship of C if A + C - B?