CREATE TABLE table_204_721 (id DECIMAL, "rank" DECIMAL, "wrestler" TEXT, "no. of reigns" DECIMAL, "combined\ defenses" DECIMAL, "combined\ days" DECIMAL)

what is the difference in the number of combined days between kevin steen and davey richards ?
SELECT ABS((SELECT "combined\ndays" FROM table_204_721 WHERE "wrestler" = 'kevin steen') - (SELECT "combined\ndays" FROM table_204_721 WHERE "wrestler" = 'davey richards'))
SELECT ABS((SELECT "combined\ndays" FROM "table_204_721" WHERE "wrestler" = 'kevin steen') - (SELECT "combined\ndays" FROM "table_204_721" WHERE "wrestler" = 'davey richards'))