CREATE TABLE table_31018 ("Team" CLOB, "Contest and round" CLOB, "Opponent" CLOB, "1st leg score*" CLOB, "2nd leg score**" CLOB, "Aggregate score" CLOB)

what is the aggregate score for the europa league play off round contest and round
SELECT "Aggregate score" FROM table_31018 WHERE "Contest and round" = 'Europa League Play Off Round'
SELECT "Aggregate score" FROM "table_31018" WHERE "Contest and round" = 'Europa League Play Off Round'