CREATE TABLE table_name_57 (date VARCHAR, result VARCHAR, opponent VARCHAR)

When has a Result of l 27-7 and an Opponent of at minnesota vikings?
SELECT date FROM table_name_57 WHERE result = "l 27-7" AND opponent = "at minnesota vikings"
SELECT "date" FROM "table_name_57" WHERE "at minnesota vikings" = "opponent" AND "l 27-7" = "result"