Among all the tweets posted from Buenos Aires, how many of them were posted on Thursdays?
"Buenos Aires" is the City; posted on Thursday refers to Weekday = 'Thursday'
SELECT COUNT(T1.TweetID) FROM twitter AS T1 INNER JOIN location AS T2 ON T2.LocationID = T1.LocationID WHERE T2.City = 'Buenos Aires' AND T1.Weekday = 'Thursday'