Complex sentence: Juliette Nadia Boulanger (16 September 188722 October 1979) was a French composer, conductor, and teacher who taught many of the leading composers and musicians of the 20th century as well as leading living composers and musicians.
Split into simpler sentences: Juliette Nadia Boulanger (16 September 188722 October 1979) was a French composer, conductor, and teacher. Among her students were many of the leading composers and musicians of the 20th century as well as celebrated living composers and musicians.