9. 8 - 2 = 6
10. 5-(-3) = 8
If you subtract a negative number, you are ADDING to the other number.
11. -9 - 4 = -13
Negative minus negative equals more negative.
12. -7 - 4
Same rule applies as 11
13. -9 -(-10) = 1
Same rule applies as 10
14. 18-(-2) = 20
Same rule applies as 10 and 13