Each of the 100 students attending a conservatory of music plays at least one of three instruments:

Question:

Each of the 100 students attending a conservatory of music plays at least one of three instruments: piano, violin, and clarinet. Of the students, 65 play the piano, 42 play the violin, 28 play the clarinet, 20 play the piano and the violin, 10 play the violin and the clarinet, and 8 play the piano and the clarinet. How many play all three instruments?