Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
Which Built at has a Date of 1946, and a 1947 Nos of 3556/7?

### Inputs:
table_name: table, columns: ['1946 Nos', '1947 Nos', 'Date', 'Built at', 'LMS Nos', 'BR Nos']

### Response:
SELECT Built at FROM table WHERE Date = 1946 AND 1947 Nos = 3556/7