what is the average number of factories and maximum number of shops for manufacturers that opened before 1990.
SELECT max(num_of_shops) ,  avg(Num_of_Factories) FROM manufacturer WHERE open_year  <  1990
average number of factories refers to AVG(num_of_factories); maximum number of shops refers to MAX(num_of_shops); manufacturers that opened before 1990 refers to open_year < 1990;