Complex sentence: He began his career with the Denver Nuggets of the ABA in 1974 where he played until 1978, and then joined the NBA's Philadelphia 76ers where he played until 1986.
Split into simpler sentences: He began his career with the Denver Nuggets of the ABA in 1974, where he played until 1978. He joined the NBA's Philadelphia 76ers, where he played until 1986.