Complex sentence: He studied at the National Academy of Rudimentary Drummers of Australia until 1974, under tutor Harry Lebler, and aged only fifteen went on to teach at the Australian Academy of Music (1974--1975).
Split into simpler sentences: He studied at the National Academy of Rudimentary Drummers of Australia until 1974, under tutor Harry Lebler. At the age of fifteen, he began to teach at the Australian Academy of Music (1974--1975).