Complex sentence: Maestro Guthrie was the son of James A. Guthrie, publisher of the San Bernardino Sun. He began his musical career at the age of fifteen and his conducting career that spanned more than six decades.
Split into simpler sentences: Maestro Guthrie was the son of James A. Guthrie, publisher of the San Bernardino Sun, began his musical careet at the age of fifteen. His conducting career that spanned more than six decades.