Complex sentence: Cook played high school basketball at Lincoln Community High School in central Illinois where he led the Railsplitters to the quarterfinals of the Illinois High School Association class AA state boys basketball tournament.
Split into simpler sentences: Cook played high school basketball at Lincoln High School in central Illinois. He led his high school team, the Lincoln Community High School Railsplitters, to the quarterfinals of the Illinois High School Association class AA state boys basketball tournament.