8 + -3
-4 + 7 =
-13 + 13
-12 + -3
-9 + 3
-6 + -7
-9 + 5
-4 + -8
5 + ( -9)
-15 + 2
-8 + 12
19 + 17
-21 + -14
8 + (-20)
13 + (-17)