CREATE TABLE table_8432 ("Number" TEXT, "Builder" TEXT, "Type" TEXT, "Date" FLOAT, "Length" TEXT, "Capacity" TEXT)

Which Date has a Length of feet 9inches (m), and a Builder of portland terminal company?
SELECT AVG("Date") FROM table_8432 WHERE "Length" = 'feet 9inches (m)' AND "Builder" = 'portland terminal company'
SELECT AVG("Date") FROM "table_8432" WHERE "Builder" = 'portland terminal company' AND "Length" = 'feet 9inches (m)'