What was Andretti's finish the year he started 16th with a Buick engine?
CREATE TABLE "indy_500_results" (
  "year" real,
  "chassis" text,
  "engine" text,
  "start" text,
  "finish" text
);
SELECT "finish" FROM "indy_500_results" WHERE "engine"='buick' AND "start"='16th';