Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| District | Incumbent | Party | First elected | Result | Candidates |
| --- | --- | --- | --- | --- | --- |
| Louisiana 1 | Bob Livingston | Republican | 1977.0 | Re-elected | Bob Livingston (R) Unopposed |
| Louisiana 2 | Lindy Boggs | Democratic | 1973.0 | Re-elected | Lindy Boggs (D) Unopposed |
| Louisiana 3 | Dave Treen | Republican | 1972.0 | Re-elected | Dave Treen (R) Unopposed |
| Louisiana 5 | Jerry Huckaby | Democratic | 1976.0 | Re-elected | Jerry Huckaby (D) Unopposed |
| Louisiana 6 | Henson Moore | Republican | 1974.0 | Re-elected | Henson Moore (R) Unopposed |
| Louisiana 7 | John Breaux | Democratic | 1972.0 | Re-elected | John Breaux (D) Unopposed |
Question:
What district did Dave Treen serve?
Answer:
Louisiana 3