What 500 yard Freestyle has a Combined of palo verde, and a 100 yard Butterfly of edward kollar (douglas)?
CREATE TABLE "swimming_and_diving" (
  "combined" text,
  "50_yard_freestyle" text,
  "100_yard_freestyle" text,
  "200_yard_freestyle" text,
  "500_yard_freestyle" text,
  "100_yard_backstroke" text,
  "100_yard_butterfly" text
);
SELECT "500_yard_freestyle" FROM "swimming_and_diving" WHERE "combined"='palo verde' AND "100_yard_butterfly"='edward kollar (douglas)';