conversations.from: human
conversations.value: There are 400 students. 120 students take dance as their elective. 200 students take art as their elective. The rest take music. What percentage of students take music?
  Give me a solution to this problem
conversations.from: assistant
conversations.value: There are 400-120-200=80 students in music.
  Thus, students in music make up (80/400)*100=20% of the students.