What are the average points for the Project Indy team that has the Ford xb engine?
CREATE TABLE "cart" (
  "year" real,
  "team" text,
  "chassis" text,
  "engine" text,
  "rank" text,
  "points" real
);
SELECT AVG("points") FROM "cart" WHERE "engine"='ford xb' AND "team"='project indy';