user: Question: 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?
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']
Types: ['text', 'text', 'real', 'text', 'real', 'real', 'real', 'real', 'real', 'real', 'real', 'real', 'real', 'real', 'text']
Sample row: ['Ferrari', 'M6', 4308.0, 'Petrol', 22.9, 10.6, 15.2, 12.3, 26.7, 18.6, 10.2, 22.2, 15.5, 345.0, 'G']
SQL:

assistant: 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;