In a certain code language, '-' represents '+', '+' represents 'x', 'x' represents '÷' and '÷' represents '-'. Find out the answer to the following question.
In this question, some equations are solved on the basis of a certain system. On the same basis find out the correct answer from amongst the four alternatives for the unsolved equation.
P is the brother of Q. Q is the brother of R. P is the son of S. Based these three statements, much of the following statements cannot be definitely true?