Which Opened is the highest one that has a Themed Area of aerial park, and a Manufacturer of zamperla?
CREATE TABLE "roller_coasters" (
  "name" text,
  "style" text,
  "opened" real,
  "manufacturer" text,
  "themed_area" text
);
SELECT MAX("opened") FROM "roller_coasters" WHERE "themed_area"='aerial park' AND "manufacturer"='zamperla';