Simplify the following text for a Grade 14 native English-speaking person.
Original: n Sinh Cung and also known as Nguyá '' n Ã i Quá '' ` c ( 19 May 1890 â `` 2 September 1969 ) was a Vietnamese Marxist revolutionary leader who was prime minister ( 1945 â `` 1955 ) and president ( 1945 â `` 1969 ) of the Democratic Republic of Vietnam ( North Vietnam ) .
Simplified: n Sinh Cung , ( May 19 , 1890 - September 2 , 1969 ) was the leader ( Prime Minister from 1945-1955 , and President from 1945-1969 ) of the Democratic Republic of Vietnam ( later the Socialist Republic of Vietnam ) .