12. Based on the first three lines, establish the rule by which the number $c$ is obtained from the numbers $a$ and $b$, and fill in the missing numbers in the empty cells:

| $a$ | $b$ | $c$ |
| :---: | :---: | :---: |
| 5 | -11 | 6 |
| $-2.7$ | $-2.3$ | 5 |
| 32 | -18 | -14 |
| -17 | 5 |  |
| 14 | -14 |  |
12. Obviously, $c=-(a+b)$, so the missing numbers are $-(-17+5)=12$; $-(14-14)=0$.