-9+5 = -4
14+(-16) = -2
-15+20 = -5
-12-8 = -20
-13+6 = -7
16-20 = -4
17+(-13) = 4
6-8 = -2
-12 + 4 = -8
-3-6 = -9
-7+10 = 3
10+(-6)=4
-7-5 = -12
23+(-25) = -2
-20+7 = -13
18-14 = 4
-10+13 = 3
34+(-16) = 18
9-12 = -3
-17+23 = 6
-14-4 = -18
-23+7 = -15