Complex sentence: Timothy Franz Geithner (born August 18,1961) is an American economist and central banker who has been the 75th United States Secretary of the Treasury since 2009, serving under President Barack Obama.
Split into simpler sentences: Timothy Franz Geithner (born August 18,1961) is an American economist and central banker. He is the 75th and current United States Secretary of the Treasury, serving under President Barack Obama.