Complex sentence: Douglas's career was based in the United Kingdom, where his single "Kung Fu Fighting" ranked number one in both the U.K. Singles Chart and the U.S. "Billboard" Hot 100 in 1974.
Split into simpler sentences: Douglas's career was based in the United Kingdom. His single "Kung Fu Fighting" ranked number one on both the U.K. Singles Chart and the U.S. "Billboard" Hot 100 in 1974.