Each of the three digits in the right column relates to the numbers in the left column.
What number belongs in the blank space?
| 4 2 3 | 3 |
| 7 0 8 | 5 |
| 9 7 5 | 7 |
| 6 1 5 |
| 4 2 3 | 3 |
| 7 0 8 | 5 |
| 9 7 5 | 7 |
| 6 1 5 |