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_48 (attendance INTEGER, visitor VARCHAR, date VARCHAR)
### Question:
How many Attendances that has a Visitor of philadelphia on may 20?
### Answer:
SELECT AVG(attendance) FROM table_name_48 WHERE visitor = "philadelphia" AND date = "may 20"