every student of a certain school must play an instrument . in last year , 1 / 2 of the students picked a woodwind instrument , 2 / 5 of the students picked a brass instrument , and all of the other students took percussion . in this year , 1 / 2 of the students who play woodwind and 1 / 4 of the students who play brass instruments left school , other students did not leave , and no fresh student come in . what fraction of all students play either a woodwind or brass instrument ?
lets pick smart numbers . total number of students : 20 woodwind ( 1 / 2 ) : 10 brass ( 2 / 5 ) : 8 percussion ( 1 / 10 ) : 2 after leaving school woodwind : 5 brass : 6 percussion : 2 new total number of students : 13 woodwind and brass : 11 answer 11 / 13 or d
divide(add(subtract(subtract(1, divide(const_1, const_2)), divide(divide(const_1, const_2), 2)), subtract(divide(const_2, 5), divide(divide(const_2, 5), 4))), subtract(subtract(1, subtract(subtract(1, divide(const_1, const_2)), divide(divide(const_1, const_2), 2))), subtract(subtract(1, divide(const_1, const_2)), divide(const_2, 5))))