2nd career/salary of substitute teacher ($20,000) involves what 6th career/salary?
CREATE TABLE "careers" (
  "career_card" text,
  "starting_career_salary" text,
  "2nd_career_salary" text,
  "3rd_career_salary" text,
  "4th_career_salary" text,
  "5th_career_salary" text,
  "6th_career_salary" text
);
SELECT "6th_career_salary" FROM "careers" WHERE "2nd_career_salary"='substitute teacher ($20,000)';