human
Considering the provided database schema and associated query, produce SQL code to retrieve the answer to the query. 
###Database Schema: District, Total amount of trees, Prevailing types, %, Amount of old trees, Amount of trees, that require replacement
###Question: What is the district when prevailing types, % is acer negundo — 30.22 tilia — 18.6 poplar — 15.23?
gpt
SELECT District FROM table WHERE Prevailing types, % = Acer negundo — 30.22 Tilia — 18.6 Poplar — 15.23