Given the following tables, write code using SQL to return the average weight for each adult animal:
table_1
| adult | animal | animal_id | size | |
|---|---|---|---|---|
| 0 | False | cat | 1 | M |
| 1 | True | dog | 2 | M |
| 2 | False | cat | 3 | M |
| 3 | False | fish | 4 | S |
| 4 | True | dog | 5 | L |
| 5 | True | cat | 6 | M |
| 6 | True | cat | 7 | M |
table_2
| animal_id | weight | |
|---|---|---|
| 0 | 1 | 8 |
| 1 | 2 | 10 |
| 2 | 3 | 11 |
| 3 | 4 | 1 |
| 4 | 5 | 20 |
| 5 | 6 | 12 |
| 6 | 7 | 12 |