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 (stuid VARCHAR, age INTEGER); CREATE TABLE has_pet (stuid VARCHAR)
### Question:
Find number of pets owned by students who are older than 20.
### Answer:
SELECT COUNT(*) FROM student AS T1 JOIN has_pet AS T2 ON T1.stuid = T2.stuid WHERE T1.age > 20