What is the average Grid that has a Time/Retired of +2 laps, and under 51 laps?
CREATE TABLE "race" (
  "driver" text,
  "constructor" text,
  "laps" real,
  "time_retired" text,
  "grid" real
);
SELECT AVG("grid") FROM "race" WHERE "time_retired"='+2 laps' AND "laps"<51;