what is the ngc number when the constellation is leo and the declination (j2000) is °42′13″?
CREATE TABLE "3301_3400" (
  "ngc_number" real,
  "object_type" text,
  "constellation" text,
  "right_ascension_j2000" text,
  "declination_j2000" text
);
SELECT AVG("ngc_number") FROM "3301_3400" WHERE "constellation"='leo' AND "declination_j2000"='°42′13″';