How many cars worth greater than 40000 were from the USA?
worth greater than 40000 refers to price > 40000; from the USA refers to country = 'USA'
SELECT COUNT(*) FROM price AS T1 INNER JOIN production AS T2 ON T1.ID = T2.ID INNER JOIN country AS T3 ON T3.origin = T2.country WHERE T3.country = 'USA' AND T1.price > 40000