Who is the driver whose Constructor was Era, and whose entrant was T.A.S.O. Mathieson?
CREATE TABLE "teams_and_drivers" (
  "entrant" text,
  "constructor" text,
  "chassis" text,
  "driver" text,
  "rounds" text
);
SELECT "driver" FROM "teams_and_drivers" WHERE "constructor"='era' AND "entrant"='t.a.s.o. mathieson';