Read the following information carefully and answer the following questions:
′P÷Q′ means 'P is the son of Q'.
′P×Q′ means 'P is son of Q'.
′P+Q′ means 'P is the brother of Q'.
′P−Q′ means 'P is the mother of Q'.
How is S related to T in the expression ′T+R−V+S′?