Which Compression ratio has a (none) DX 10 Name and a FOURCC of dxt4?
CREATE TABLE table_39144 (
    "FOURCC" text,
    "DX 10 Name" text,
    "Description" text,
    "Alpha premultiplied?" text,
    "Compression ratio" text,
    "Texture Type" text
)
SELECT "Compression ratio" FROM table_39144 WHERE "DX 10 Name" = '(none)' AND "FOURCC" = 'dxt4'
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 Compression ratio has a (none) DX 10 Name and a FOURCC of dxt4? ### Input: CREATE TABLE table_39144 (
    "FOURCC" text,
    "DX 10 Name" text,
    "Description" text,
    "Alpha premultiplied?" text,
    "Compression ratio" text,
    "Texture Type" text
) ### Response: SELECT "Compression ratio" FROM table_39144 WHERE "DX 10 Name" = '(none)' AND "FOURCC" = 'dxt4'