Database: public_review_platform
Question: How much time do businesses in El Mirage City, AZ State operate in average daily?
SQL: SELECT SUM(T2.closing_time - T2.opening_time) FROM Business AS T1 INNER JOIN Business_Hours AS T2 ON T1.business_id = T2.business_id WHERE T1.city = 'El Mirage' AND T1.state = 'AZ'