If P - Q means P is the sister of Q, P + R means P is the mother of R, and R × S means R is the daughter of S, what is the relationship of Q to S in the expression P - Q + R × S?
If X - Y means X is the brother of Y, X + Z means X is the sister of Z, and Y × Z means Y is the father of Z, what is the relationship of X to Z in X - Y + Z?
If X - Y means X is the sister of Y, X + Y means X is the brother of Y, and X × Y means X is the uncle of Y, what is the relationship of Z if X - Z + Y?
If A + B means A is the sister of B, A - B means A is the brother of B, and A × B means A is the mother of B, what is the relationship of C if A + B - C?