8. (6 points) The three-digit number $2 a 3$ plus 326 equals $5 b 9$. If $5 b 9$ is a multiple of 9, then $a+b=$

 untranslated portion:
```
(6 points) The three-digit number $2 a 3$ plus 326 equals $5 b 9$. If $5 b 9$ is a multiple of 9, then $a+b=$
```