CREATE TABLE table_204_880 (id DECIMAL, "year" DECIMAL, "competition" TEXT, "venue" TEXT, "position" TEXT, "event" TEXT, "notes" TEXT)

51st position and 31st position were both obtained by this runner at which competition ?
SELECT "competition" FROM table_204_880 WHERE "position" = 51
SELECT "competition" FROM "table_204_880" WHERE "position" = 51