text: Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
  ### Context:
  CREATE TABLE student (age INTEGER, stuid VARCHAR); CREATE TABLE has_pet (age INTEGER, stuid VARCHAR)
  ### Question:
  Find the average age of students who do not have any pet .
  ### Answer:
  SELECT AVG(age) FROM student WHERE NOT stuid IN (SELECT stuid FROM has_pet)