Name the sum of points for chassis of brm p160e and year more than 1974
CREATE TABLE "complete_formula_one_world_championship_" (
  "year" real,
  "entrant" text,
  "chassis" text,
  "engine" text,
  "points" real
);
SELECT SUM("points") FROM "complete_formula_one_world_championship_" WHERE "chassis"='brm p160e' AND "year">1974;