Complex sentence: Within a few years a majority of households were FM equipped, by the 1980s a majority of cars sold had FM stereo radios... and a majority of listening in the U.S. was devoted to FM signals according to the Arbitron rating service.
Split into simpler sentences: Within a few years a majority of households were FM equipped. By the 1980s a majority of cars sold had FM stereo radios, and a majority of listening in the U.S. was devoted to FM signals according to the Arbitron rating service.