-1639
-27
Well, 18 and 3 (both factors of 36) add up to 21. As well, the factors 12 and 9 add up to 21.
18 and 18
The factors of 30 are 1, 2, 3, 5, 6, 10, 15, and 30. The factors 1+3+5+10=19, 1+2+6+10=19, 1+3+15=19, and 3+6+10= 19.
Factor pairs for 18 include 1&18, 2&9, and 3&6. Only one of these pairs adds up to 11.
45 and 18
222
47
132
-21
228