Hi!  Can you show me a list of all people and their people IDs?
select name, people_id from people
Nice!  Can you filter the list to show only the people who do not have an associated entrepreneur ID?
select name, people_id from people where people_id not in ( select people_id from entrepreneur )
Wonderful!  Can you tell me what is the total amount of money requested by the people who ARE entrepreneurs?
select sum ( money_requested ) from entrepreneur