How many stars on average does user no.3 give to Yelp_Business in Arizona?
user no.3 refers to user_id = 3; in Arizona refers to state = 'AZ'; stars on average = avg(review_stars(user_id = 3))
SELECT AVG(T2.review_stars) FROM Business AS T1 INNER JOIN Reviews AS T2 ON T1.business_id = T2.business_id WHERE T1.state LIKE 'AZ' AND T2.user_id = 3