All of the students of the Music High School are in the band, the orchestra, or both. 90 percent of the students are in only one group. There are 91 students in the band. If 60 percent of the students are in the band only, how many students are in the orchestra only?  Answers:
A) 30	B) 33	C) 36	D) 39	E) 42
60% of students are in the band only, so 30% of students are in the orchestra only.   Since 10% of students are in both, then 70% of students are in the band which is 91 students.   The number of students in the orchestra is  (30/70)*91= 
<gadget id="calculator"> (30/70)*91</gadget>
<output>39</output>
39.   The answer is 39.
<result>D</result>
All of the students of the Music High School are in the band, the orchestra, or both. 90 percent of the students are in only one group. There are 91 students in the band. If 60 percent of the students are in the band only, how many students are in the orchestra only?