CREATE TABLE table_name_18 (first_elected NUMBER, district VARCHAR2, committee VARCHAR2)

What is the average first elected year that has a district of 11 and a committee of environmental matters?
SELECT AVG(first_elected) FROM table_name_18 WHERE district = "11" AND committee = "environmental matters"
SELECT AVG("first_elected") FROM "table_name_18" WHERE "11" = "district" AND "committee" = "environmental matters"