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 table_name_21 (decile VARCHAR, authority VARCHAR, name VARCHAR)
### Question:
How many deciles have an Authority of state and a Name of chertsey school?
### Answer:
SELECT COUNT(decile) FROM table_name_21 WHERE authority = "state" AND name = "chertsey school"