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_64 (b_ VARCHAR, reb_ INTEGER, no_ VARCHAR, a_ VARCHAR, ast_ VARCHAR)
### Question:
Which rebound was 8 and has and ast that was less than 57?
### Answer:
SELECT AVG(reb_)[b_] FROM table_name_64 WHERE no_[a_] = "8" AND ast_[b_] < 57