#Format : LIMIT s-1, t - (s - 1)
SELECT ROUND(ABS(x1 - x2) + ABS(y1 - y2), 4)
FROM (SELECT MIN(lon) x1, MAX(lon) x2
FROM (SELECT*FROM citytable
WHERE lat < 121.8 ORDER BY lat DESC LIMIT 3, 15) AS Table1) AS latTable,
(SELECT MIN(lat) y1, MAX(lat) y2
FROM (SELECT*FROM citytable
WHERE lon > 25.1 ORDER BY lon ASC LIMIT 3, 15) AS Table2) AS lonTable;