Complex sentence: Sarah became the youngest woman to compete in the Indianapolis 500 at age 19 in 2000, where she also became the third woman to compete in the Indianapolis 500 behind Janet Guthrie and Lyn St. James.
Split into simpler sentences: Sarah became the youngest woman to compete in the Indianapolis 500 at age 19 in 2000. She was also the third woman to compete in the Indianapolis 500 behind Janet Guthrie and Lyn St. James.