SELECT avg(Num_of_Factories) FROM manufacturer WHERE num_of_shops  >  20
Find the average number of factories for the manufacturers that have more than 20 shops.
SELECT avg ( Num_of_Factories ) FROM manufacturer WHERE num_of_shops > 20
select avg ( num_of_factories ) from manufacturer where num_of_shops > value
Find the average number of factories for the manufacturers that have more than 20 shops .