Thank you!  Can you filter this list ot show only the hometowns that have both people older than 23 years of age and people younger than 20 years of age?
SELECT Hometown FROM people WHERE Age  >  23 INTERSECT SELECT Hometown FROM people WHERE Age  <  20
hometowns with both people older than 23 and younger than 20 requires an INTERSECT of two SELECT queries, one with Age > 23 and the other with Age < 20;