13. is - 1
15. is -5
17. is 8
19. is -6
21. is 5
23. is -5
25. is -7
27. is -45
On the second sheet:
1. is -1
3. is -5
5. is 9
7. is -7
9. is 4
11. is 8
13. is 0
15. is -6
17. is -1
19. is 0
21. is 15
23. is -9
25. is 11
27. is -4
29. is 11
31. is 10
(Tip: The questions where it's "something - (-something)", is the same as "something + something", two minuses make a plus. Also, "something + (-something)" is the same as "something - something", a plus and a minus make a minus. Finally, the normal "something - something" questions is the same as finding the difference between the two numbers and sticking a minus in front of it, if the second number is bigger than the first. For example, 2 - 7. The difference is 5, and because the second number (7) is bigger than 2, you stick a minus in front (-5). However, if it was 7 - 2, it would just be 5.)
