For the gte northwest classic with the score of 207 (-9), what is the average 1st prize ($)
CREATE TABLE "tournament_results" (
  "date" text,
  "tournament" text,
  "location" text,
  "purse" real,
  "winner" text,
  "score" text,
  "1st_prize" real
);
SELECT AVG("1st_prize") FROM "tournament_results" WHERE "score"='207 (-9)' AND "tournament"='gte northwest classic';