In a certain code language: 'C - D' means 'C is the father of D', 'C + D' means 'C is the sister of D', 'C $ D' means 'C is the mother of D', 'C % D' means 'C is the brother of D'. Based on the above, how is L related to O in the expression 'L - M + N - O'?

In a certain code language: 'A + B' means 'A is the son of B' 'A - B' means 'A is the brother of B' 'A × B' means 'A is the wife of B' 'A ÷ B' means 'A is the father of B' Based on the above, how is L related to P if the expression is 'L + M ÷ N × O - P'?

A man said, 'The boy playing with my son is the son of my wife's sister.' How is the boy related to the man?