Complex sentence: He prepared a successful audition in a matter of weeks, and only four years later, a surprisingly short time by the standards of the day, still a teenager, he left with a prize of 300 francs for solo playing.
Split into simpler sentences: He prepared a successful audition in a matter of weeks. Only four years later, a surprisingly short time by the standards of the day, he left with a prize of 300 francs for solo playing.