CREATE TABLE table_30898 ("Episode" FLOAT, "First Air Date" TEXT, "Rating  ( 18\\u201349 ) " TEXT, "Share  ( 18\\u201349 ) " FLOAT, "Viewers  ( millions ) " TEXT, "Rank  ( timeslot ) " TEXT)

When 4.5 is the rating (18-49) what is the air date?
SELECT "First Air Date" FROM table_30898 WHERE "Rating (18\u201349)" = '4.5'
SELECT "First Air Date" FROM "table_30898" WHERE "Rating (18\u201349)" = '4.5'