CREATE TABLE table_15192 ("Year" FLOAT, "Entrant" TEXT, "Chassis" TEXT, "Engine" TEXT, "Points" FLOAT)

What is the average year that the Belanger Motors had an Offenhauser l4 engine?
SELECT AVG("Year") FROM table_15192 WHERE "Engine" = 'offenhauser l4' AND "Entrant" = 'belanger motors'
SELECT AVG("Year") FROM "table_15192" WHERE "Engine" = 'offenhauser l4' AND "Entrant" = 'belanger motors'