what is the difference in speed number of the fastest and slowest trains in km/h ?
CREATE TABLE table_204_821 (
    id number,
    "speed [km/h (mph)]" text,
    "train" text,
    "type" text,
    "location" text,
    "date" text,
    "comments" text
)
SELECT MAX("speed [km/h (mph)]") - MIN("speed [km/h (mph)]") FROM table_204_821
Below are sql tables schemas paired with instruction that describes a task. Using valid SQLite, write a response that appropriately completes the request for the provided tables. ### Instruction: what is the difference in speed number of the fastest and slowest trains in km/h ? ### Input: CREATE TABLE table_204_821 (
    id number,
    "speed [km/h (mph)]" text,
    "train" text,
    "type" text,
    "location" text,
    "date" text,
    "comments" text
) ### Response: SELECT MAX("speed [km/h (mph)]") - MIN("speed [km/h (mph)]") FROM table_204_821