Simplify the following text for a Grade 6 native English-speaking person.
Original: Mahmoud Abbas ( , ; born 26 March 1935 ) , also known by the kunya Abu Mazen , has been the Chairman of the Palestine Liberation Organisation ( PLO ) since 11 November 2004 and became President of the Palestinian National Authority on 15 January 2005 on the Fatah ( Ù Ø Ø Fataá ) ticket .
Simplified: Mahmoud Abbas ( Arabic : Ù Ù Ø Ø Ø Ø Ø â ) ( born March 26 , 1935 ) , also known by the Kunya Abu Mazen ( Ø Ø Ù Ù