Complex sentence: The duo's early career included a stint with Jay and the Americans, for which they used pseudonyms, and in the early 1970s as pop songwriters for ABC/Dunhill Records, which released all of Steely Dan's 1970s albums.
Split into simpler sentences: The duo's early career included a stint with Jay and the Americans, for which they used pseudonyms. In the early 1970s they worked as pop songwriters for ABC/Dunhill Records, which released all of Steely Dan's 1970s albums.