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

### Instruction:
With a Type of 4-6-4t, what is the sum Withdrawn?

### Inputs:
table_name: table, columns: ['Locomotive', 'Type', 'Builder', "Builder's No.", 'Built', 'Entered service', 'Withdrawn']

### Response:
SELECT SUM Withdrawn FROM table WHERE Type = 4-6-4t