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_98 (platform INTEGER, frequency__per_hour_ VARCHAR, destination VARCHAR)
### Question:
what is the platform when the frequency (per hour) is 4 and the destination is west croydon?
### Answer:
SELECT SUM(platform) FROM table_name_98 WHERE frequency__per_hour_ = 4 AND destination = "west croydon"