CREATE TABLE table_31824 ("Week" FLOAT, "Date" CLOB, "Opponent" CLOB, "Result" CLOB, "Venue" CLOB, "Attendance" FLOAT, "Record" CLOB)

Tell mem the opponent for result of w 31-21
SELECT "Opponent" FROM table_31824 WHERE "Result" = 'w 31-21'
SELECT "Opponent" FROM "table_31824" WHERE "Result" = 'w 31-21'