CREATE TABLE table_38503 ("Borough" TEXT, "Components" TEXT, "Population" FLOAT, "Number of Borough Councilors" FLOAT, "Number of Municipal Councilors" FLOAT)

What is the average number of borough councilors from Brompton?
SELECT AVG("Number of Borough Councilors") FROM table_38503 WHERE "Borough" = 'brompton'
SELECT AVG("Number of Borough Councilors") FROM "table_38503" WHERE "Borough" = 'brompton'