CREATE TABLE trip (start_station_id VARCHAR2)
CREATE TABLE station (lat NUMBER, long NUMBER, id VARCHAR2)

What is the average latitude and longitude of the starting points of all trips?
SELECT AVG(T1.lat), AVG(T1.long) FROM station AS T1 JOIN trip AS T2 ON T1.id = T2.start_station_id
SELECT AVG("T1"."lat"), AVG("T1"."long") FROM "station" "T1" JOIN "trip" "T2" ON "T1"."id" = "T2"."start_station_id"