Show the average duration of trips starting from each station id.
select start_station_id, avg(duration) from trip group by start_station_id
For each station, return its longitude and the average duration of trips that started from the station.
select t1.name, t1.long, avg(t2.duration) from station as t1 join trip as t2 on t1.id = t2.start_station_id group by t2.start_station_id