When the Mole was Petrina Edge, what was the potential prize money?
CREATE TABLE "australia" (
  "season" real,
  "year" real,
  "mole" text,
  "winner" text,
  "runner_up" text,
  "total_prize_money" text,
  "potential_prize_money" text,
  "destination" text
);
SELECT "potential_prize_money" FROM "australia" WHERE "mole"='petrina edge';