Stuck right at the end! any ideas?
https://ibb.co/zPKzLPk
*-------------------------------*
| 1 28 4 | 5 6 23 | 38 7 9 |
| 5 28 7 | 23 9 4 | 1 38 6 |
| 9 3 6 | 7 1 8 | 4 5 2 |
|---------+---------+-----------|
| 2 7 8 | 1 4 9 | 5 6 3 |
| 3 6 9 | 8 2 5 | 7 4 1 |
| 4 1 5 | 6 3 7 | 9 2 8 |
|---------+---------+-----------|
| 6 5 23 | 9 7 1 |*3-28 38 4 |
| 7 9 23 | 4 8 23 | 6 1 5 |
| 8 4 1 | 23 5 6 | 23 9 7 |
*-------------------------------*