Simplify the following text for a Grade 7 native English-speaking person.
Original: Lyndon Baines Johnson ( August 27 , 1908 - January 22 , 1973 ) , often referred to as LBJ , was a US politician who served as the 36th President of the United States ( 1963-1969 ) after his service as the 37th Vice President of the United States ( 1961-1963 ) .
Simplified: Lyndon B. Johnson ( August 27 , 1908 â `` January 22 , 1973 ) was the 36th president of the United States .