CREATE TABLE table_58163 ("Platform" FLOAT, "Frequency  ( per hour ) " FLOAT, "Destination" TEXT, "Operator" TEXT, "Line" TEXT)

what is the platform when the frequency (per hour) is 4 and the destination is west croydon?
SELECT SUM("Platform") FROM table_58163 WHERE "Frequency (per hour)" = '4' AND "Destination" = 'west croydon'
SELECT SUM("Platform") FROM "table_58163" WHERE "Destination" = 'west croydon' AND "Frequency (per hour)" = '4'