CREATE TABLE table_51784 ("Week" FLOAT, "Date" CLOB, "Opponent" CLOB, "Result" CLOB, "Attendance" FLOAT)

Which Attendance has a Result of w 51-21?
SELECT "Attendance" FROM table_51784 WHERE "Result" = 'w 51-21'
SELECT "Attendance" FROM "table_51784" WHERE "Result" = 'w 51-21'