Complex sentence: The cost of large and complex twin-engine fighters in the 1960s and 1970s prompted the development of the relatively light General Dynamics F-16 Fighting Falcon in the late 1970s.
Split into simpler sentences: The cost of large and complex twin-engine fighters in the 1960s and 70s. It prompted the development of the relatively light General Dynamics F-16 Fighting Falcon in the late 1970s.