Describe the ages, genders and numbers of events participated by the users at coordinates of (-102,38).
coordinates of (-102,38) refers to longitude = -102, latitude = 38;
SELECT DISTINCT T1.age, T1.gender, COUNT(T2.event_id) FROM gender_age AS T1 INNER JOIN `events` AS T2 ON T2.device_id = T1.device_id WHERE T2.longitude = -102 AND T2.latitude = 38 GROUP BY T1.age, T1.gender, T2.longitude, T2.latitude