Factors are numbers you can multiply together to get another number.
28: 1, 2, 4, 14, 7, 28
2 + 7 = 9. The two factors of 28 that add up to 9 are 2 and 7.
They are 7 and 2
-8
Add them up. The factors of 9 are 1, 3 and 9. The sum of the factors is 13.
6 and 9
How about 3 and 6
268
The factors of 9 are 1, 3, and 9. 1 + 3 + 9 = 13
9 and -3
5
7 and 2
9
You are 9.