Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_name_81 (l_100km_combined INTEGER, mpg_uk_extra_urban VARCHAR, l_100km_urban__cold_ VARCHAR, mpg_uk_combined VARCHAR)

### 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?

### Accurate SQL ###

SELECT AVG(l_100km_combined) FROM table_name_81 WHERE l_100km_urban__cold_ = 13.9 AND mpg_uk_combined > 28.5 AND mpg_uk_extra_urban < 38.7