Simplify the following text for a Grade 12 native English-speaking person.
Original: Gertrude Baines ( April 6 , 1894 â `` September 11 , 2009 ) was an American supercentenarian , who was the oldest recognized living person according to Guinness World Records , from January 2 , 2009 , the death of Portuguese woman Maria de Jesus , until her own death on September 11 , 2009 , at age 115 years 158 days .
Simplified: Gertrude Baines ( April 6 , 1894 -- September 11 , 2009 ) was an American woman who was believed to have been the oldest person in the world from the death of Portuguese woman Maria de Jesus on January 2 , 2009 until her death on September 11 , 2009 .