CREATE TABLE table_18839 ("Club" TEXT, "Played" TEXT, "Won" TEXT, "Drawn" TEXT, "Lost" TEXT, "Points for" TEXT, "Points against" TEXT, "Tries for" TEXT, "Tries against" TEXT, "Try bonus" TEXT, "Losing bonus" TEXT, "Points" TEXT)

How many tries for when the points against was 547?
SELECT "Tries for" FROM table_18839 WHERE "Points against" = '547'
SELECT "Tries for" FROM "table_18839" WHERE "Points against" = '547'