CREATE TABLE table_51107 ("Rider" TEXT, "Manufacturer" TEXT, "Laps" FLOAT, "Time" TEXT, "Grid" FLOAT)

Count the Grid which has a Manufacturer of aprilia, and a Rider of bradley smith?
SELECT AVG("Grid") FROM table_51107 WHERE "Manufacturer" = 'aprilia' AND "Rider" = 'bradley smith'
SELECT AVG("Grid") FROM "table_51107" WHERE "Manufacturer" = 'aprilia' AND "Rider" = 'bradley smith'