In a certain code language,
'A + B' means 'A is the daughter of B',
'A - B' means 'A is the husband of B',
'A × B' means 'A is the mother of B' and
'A ÷ B' means 'A is the father of B'.
How is B related to D, if A×B+C÷D?

Let's break down the expression A×B+C÷D step by step:
A×B: A is the mother of B. (A is Female)

B+C: B is the daughter of C. (B is Female)

Since A is the mother of B and B is the daughter of C, C must be the father of B, making A and C husband and wife (A [Female]↔C [Male]).

C÷D: C is the father of D.

From the above points:

C is the father of both B and D.

B is a female (daughter of C).

Therefore, B is the sister of D.