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 products ( code number, name text, price number, manufacturer number )
TABLE: CREATE TABLE manufacturers ( code number, name text, headquarter text, founder text, revenue number )

### Question ###
What is the total revenue of companies started by founder?

### Accurate SQL ###

SELECT SUM(revenue), founder FROM manufacturers GROUP BY founder