Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_55849 ( "Presidency" real, "President" text, "Date of Birth" text, "Took office" real, "Left office" text )

### Question ###
What is the Took Office Date of the Presidency that Left Office Incumbent?

### Accurate SQL ###

SELECT SUM("Took office") FROM table_55849 WHERE "Left office" = 'incumbent'