Which engine of Rob Walker Racing Team has 47 points and F tyres?
CREATE TABLE table_49309 (
    "Year" real,
    "Entrant" text,
    "Chassis" text,
    "Engine" text,
    "Tyres" text,
    "Points" text
)
SELECT "Engine" FROM table_49309 WHERE "Points" = '47' AND "Tyres" = 'f' AND "Entrant" = 'rob walker racing team'
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: Which engine of Rob Walker Racing Team has 47 points and F tyres? ### Input: CREATE TABLE table_49309 (
    "Year" real,
    "Entrant" text,
    "Chassis" text,
    "Engine" text,
    "Tyres" text,
    "Points" text
) ### Response: SELECT "Engine" FROM table_49309 WHERE "Points" = '47' AND "Tyres" = 'f' AND "Entrant" = 'rob walker racing team'