Complex sentence: Southeast Airlines, was a low fare public charter airline in the United States, headquartered in Largo, Florida, operating regular service to various vacation/leisure destinations using seven Douglas DC-9 and four McDonnell Douglas MD-80 aircraft.
Split into simpler sentences: Southeast Airlines, was a low fare public charter airline in the United States, headquartered in Largo, Florida, operating regular service to various vacation/leisure destinations. Using seven Douglas DC-9 and four McDonnell Douglas MD-80 aircraft.