CREATE TABLE Manufacturers (Code NUMBER, Name VARCHAR2, Headquarter VARCHAR2, Founder VARCHAR2, Revenue FLOAT)
CREATE TABLE Products (Code NUMBER, Name VARCHAR2, Price NUMBER, Manufacturer NUMBER)

For those records from the products and each product's manufacturer, a bar chart shows the distribution of headquarter and the average of revenue , and group by attribute headquarter, sort from high to low by the mean revenue.
SELECT Headquarter, AVG(Revenue) FROM Products AS T1 JOIN Manufacturers AS T2 ON T1.Manufacturer = T2.Code GROUP BY Headquarter ORDER BY AVG(Revenue) DESC
SELECT "Headquarter", AVG("Revenue") FROM "Products" "T1" JOIN "Manufacturers" "T2" ON "T1"."Manufacturer" = "T2"."Code" GROUP BY "Headquarter" ORDER BY AVG("Revenue") DESC