CREATE TABLE table_17123 ("Team" TEXT, "Outgoing manager" TEXT, "Manner of departure" TEXT, "Date of vacancy" TEXT, "Replaced by" TEXT, "Date of appointment" TEXT)

How many have been replaced where the appointment date is 10 December 2007 and the manner of departure is quit?
SELECT COUNT("Replaced by") FROM table_17123 WHERE "Date of appointment" = '10 December 2007' AND "Manner of departure" = 'Quit'
SELECT COUNT("Replaced by") FROM "table_17123" WHERE "Date of appointment" = '10 December 2007' AND "Manner of departure" = 'Quit'