How many people voted for Obama in the county where McCain got 72.75% of the votes?
CREATE TABLE "by_county" (
  "county" text,
  "obamapct" text,
  "obamanum" real,
  "mc_cainpct" text,
  "mc_cainnum" real
);
SELECT MIN("obamanum") FROM "by_county" WHERE "mc_cainpct"='72.75%';