Write SQL query to solve given problem: Among the stations with 3 stores, how many stations have a station pressure of no more than 30 on February 18, 2014?. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT COUNT(station_nbr) FROM weather WHERE `date` = '2014-02-18' AND stnpressure < 30 AND station_nbr IN ( SELECT station_nbr FROM relation GROUP BY station_nbr HAVING COUNT(store_nbr) = 3 )