268
The distinct prime factors of 550 are 2, 5 and 11. They add up to 18.
153
715
The factors of 15 are: 1, 3, 5, 15 The factors of 18 are: 1, 2, 3, 6, 9, 18
268
23
The distinct prime factors of 550 are 2, 5 and 11. They add up to 18.
23
Factors of 250 that add up to 8 = 1 + 2 + 5
212
1012
35
They are: 2+3 = 5
First list the factors of each. For 18, that's 1, 2, 3, 6, 9, and 18. For 20, that's 1, 2, 4, 5, 10, and 20. From these, you could add all of the factors of 18 to get 39. Or you could add 20, 10, and 9. Or 20, 10, 5, and 4. Or . . . you get the idea.
31
15 and 4 are the factors of 120 that add up to 19.