CREATE TABLE table_name_98 (platform INT, frequency__per_hour_ VARCHAR, destination VARCHAR)

what is the platform when the frequency (per hour) is 4 and the destination is west croydon?
SELECT SUM(platform) FROM table_name_98 WHERE frequency__per_hour_ = 4 AND destination = "west croydon"
SELECT SUM("platform") FROM "table_name_98" WHERE "destination" = "west croydon" AND "frequency__per_hour_" = 4