What are the opening hours of business number 53 on Friday?
opening hours refers to opening_time; business number refers to business_id; Friday refers to day_of_week = 'Friday';
SELECT T1.closing_time - T1.opening_time AS "opening hours" FROM Business_Hours AS T1 INNER JOIN Days AS T2 ON T1.day_id = T2.day_id WHERE T2.day_of_week LIKE 'Friday' AND T1.business_id = 53