After a few days of absence on the forum because of the work I had to do on my website, here is again a (medium) puzzle to solve .
.5..9....1......7......6.8...9.1...54..37.........8.2.8.3.....1.6..4....7..2...9.
puzzle: Show
Good resolution.
Robert
+----------------------+---------------------+---------------------+
| 236 5 2468 | 1478 9 1347 | 12346 1346 2346 |
| 1 23489 2468 | 458 238 345 | 234569 7 23469 |
| 239 23479 247 | 15 23 6 | 15 8 2349 |
+----------------------+---------------------+---------------------+
| 236 78 9 | 46 1 24 | 78 346 5 |
| 4 128 12568 | 3 7 259 | 1689 16 689 |
| 356 137 1567 | 4569 56 8 | 134679 2 34679 |
+----------------------+---------------------+---------------------+
| 8 24(9) 3 | (5679) (56) (579) | 247 4(5) 1 |
| 2-5(9) 6 125 | 15789 4 13579 | 2378 3(5) 2378 |
| 7 14 145 | 2 38 135 | 3468 9 3468 |
+----------------------+---------------------+---------------------+
*-------------------------------------------------------------*
| 236 5 2468 | 1478 9 1347 | 12346 a1346 2346 |
| 1 23489 2468 | 458 238 345 | 234569 7 23469 |
| 239 23479 247 | 15 23 6 | 15 8 2349 |
|--------------------+-------------------+--------------------|
| 236 78 9 | 46 1 24 | 78 a346 5 |
| 4 128 12568 | 3 7 259 | 1689 a16 689 |
| 356 137 1567 | 4569 56 8 | 134679 2 34679 |
|--------------------+-------------------+--------------------|
| 8 c249 3 |b5679 b56 b579 | 247 b45 1 |
| 29-5 6 c125 | 15789 4 13579 | 2378 a35 2378 |
| 7 c14 c145 | 2 38 135 | 3468 9 3468 |
*-------------------------------------------------------------*
+------------------------+------------------------+--------------------------+
| 236 5 2468 | 1478 9 1347 | 12346 1346 2346 |
| 1 23489 2468 | 458 238 345 | 234569 7 23469 |
| 239 23479 247 | 15 23 6 | 15 8 2349 |
+------------------------+------------------------+--------------------------+
| 236 78 9 | 46 1 24 | 78 346 5 |
| 4 128 12568 | 3 7 259 | 1689 16 689 |
| c356 137 1567 | 4569 b56 8 | 134679 2 34679 |
+------------------------+------------------------+--------------------------+
| 8 e249 3 | 5679 a56 579 | e247 e4-5 1 |
| d259 6 125 | 15789 4 13579 | 2378 35 2378 |
| 7 14 145 | 2 38 135 | 3468 9 3468 |
+------------------------+------------------------+--------------------------+
Cenoman wrote:(5)r7c5 = r6c5 - r6c1 = (5-9)r8c1 =(924)r7c278 => -5 r7c8; ste