Complex sentence: In 1990 many of Kmart's stores were considered to be outdated and in decaying condition, that led Kmart to change their image and logo which was unveiled in September 1990, and stores in 1991.
Split into simpler sentences: In 1990 many of Kmart's stores were considered to be outdated and in decaying condition. That led Kmart to change their image and logo which was unveiled in September 1990, and stores in 1991.