-90
Different signs show it would have values subtracted to get the 18.
1,72=71
2,36=34
3,24=21
4,18=14
6,12=6
8,9=1
There are none that work so if you are factoring then it would be prime.
6 + 12 = 18 6 * 12 = 72
-86
-27
24 and 3
21
24
7
-73
{1, 53 and 72 lots of -1} ie 1*53*-1*-1*-1 ... *-1
6 and -3.
78
1308