Complex sentence: He was previously Prime Minister from 2007 to 2010, and Labor Leader from 2006 to 2010; he is the first former Prime Minister to return to the office since Robert Menzies in 1949.
Split into simpler sentences: He was previously Prime Minister from 2007 to 2010, and Labor Leader from 2006 to 2010. He is the first former Prime Minister to return to the office since Robert Menzies in 1949.