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

### Instruction:
What is the highest Quantity for PTRD Nos. 3, 15?

### Inputs:
table_name: table, columns: ['Manufacturer', 'Type', 'Quantity', 'PTRD Nos.', 'GWR Nos.']

### Response:
SELECT MAX Quantity FROM table WHERE PTRD Nos. = 3, 15