How many sales had a peak position more than 2 and a Certification of 3x platinum?
CREATE TABLE "top_10_american_albums" (
  "rank" real,
  "artist" text,
  "album" text,
  "peak_position" real,
  "sales" real,
  "certification" text
);
SELECT COUNT("sales") FROM "top_10_american_albums" WHERE "peak_position">2 AND "certification"='3x platinum';