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

### Instruction:
What's the average L/km combines when the L/100km Urban is 13.9, the mpg-UK combined is more than 28.5 and the mpg-UK extra urban is less than 38.7?

### Inputs:
table_name: table, columns: ['Manufacturer', 'Transmission', 'Engine Capacity', 'Fuel Type', 'L/100km Urban (Cold)', 'L/100km Extra-Urban', 'L/100km Combined', 'mpg-UK Urban (Cold)', 'mpg-UK Extra-Urban', 'mpg-UK Combined', 'mpg-US Urban', 'mpg-US Extra-Urban', 'mpg-US Combined', 'CO 2 g/km', 'Green Rating']

### Response:
SELECT AVG L/100km Combined FROM table WHERE L/100km Urban (Cold) = 13.9 AND mpg-UK Combined > 28.5 AND mpg-UK Extra-Urban < 38.7