Complex sentence: The Sands Regency began a major renovation in 2005 and Herbst Gaming finished it in 2007, they also renovated and expanded Rail City, of which Sands Regent started.
Split into simpler sentences: The Sands Regency began a major renovation in 2005, and Herbst Gaming finished it in 2007. They also renovated and expanded Rail City, of which Sands Regent started.