Complex sentence: Air West later became Hughes Airwest which was subsequently merged into Republic Airlines in 1980, which in turn was acquired by Northwest Airlines in 1987, and the finally became part of Delta Airlines in 2008.
Split into simpler sentences: Air West later became Hughes Airwest which was subsequently merged into Republic Airlines in 1980. Repblic in turn was acquired by Northwest Airlines in 1987 which was then merged into Delta Airlines in 2008.