CREATE TABLE table_6713 ("Season" TEXT, "Competition" TEXT, "Round" TEXT, "Opponent" TEXT, "Home" TEXT, "Away" TEXT, "Agg." TEXT)

Which Away has an Opponent of slavia prague?
SELECT "Away" FROM table_6713 WHERE "Opponent" = 'slavia prague'
SELECT "Away" FROM "table_6713" WHERE "Opponent" = 'slavia prague'