La
suma
de
dos
números
(
+
5
)
+
(
-
6
)
=
-
1
(
-
12
)
+
(
+
8
)
=
-
____________________
(
-
9
)
+
(
-
7
)
=
-
____________________
(
-
4
)
+
(
-
4
)
=
-
____________________
(
6
)
+
(
-
8
)
=
-
____________________
(
5
)
+
(
-
20
)
=
-
____________________
(
3
)
+
(
-
4
)
=
-
1
