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?  Answers:
A) 7/13  B) 4/5  C) 9/13  D) 11/13  E) 7/10
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 11/13
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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?