What is the total number of Area (km²), when Population (2007) is 6,176?
CREATE TABLE "political_subdivision" (
  "barangay" text,
  "area_km" real,
  "population_2007" real,
  "population_2010" real,
  "pop_density_per_km" real
);
SELECT COUNT("area_km") FROM "political_subdivision" WHERE "population_2007"='6,176';