what is the sum of tonnage when the type of ship is twin screw ro-ro motorship and the date entered service is 11 february 1983?
CREATE TABLE table_55399 (
    "Ship's name" text,
    "Date entered service" text,
    "Date withdrawn" text,
    "Tonnage" real,
    "Type of Ship" text
)
SELECT SUM("Tonnage") FROM table_55399 WHERE "Type of Ship" = 'twin screw ro-ro motorship' AND "Date entered service" = '11 february 1983'
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 sum of tonnage when the type of ship is twin screw ro-ro motorship and the date entered service is 11 february 1983? ### Input: CREATE TABLE table_55399 (
    "Ship's name" text,
    "Date entered service" text,
    "Date withdrawn" text,
    "Tonnage" real,
    "Type of Ship" text
) ### Response: SELECT SUM("Tonnage") FROM table_55399 WHERE "Type of Ship" = 'twin screw ro-ro motorship' AND "Date entered service" = '11 february 1983'