CREATE TABLE table_76997 ("Date" TEXT, "Opponents" TEXT, "H / A" TEXT, "Result F \\u2013 A" TEXT, "Attendance" FLOAT)

How many people attended the match when Manchester United played against the Hearts?
SELECT SUM("Attendance") FROM table_76997 WHERE "Opponents" = 'hearts'
SELECT SUM("Attendance") FROM "table_76997" WHERE "Opponents" = 'hearts'