Erbijsommen en erafsommen tot 20 oplossen
In de mix
1.
12
0
+
=
2.
17
16
–
=
3.
12
0
+
=
4.
15
12
–
=
5.
13
12
–
=
6.
13
12
–
=
7.
15
14
–
=
8.
15
13
–
=
9.
14
13
–
=
10.
16
1
+
=
11.
16
1
+
=
12.
15
4
+
=
13.
13
12
–
=
14.
18
12
–
=
15.
17
2
+
=
16.
12
6
+
=
17.
15
5
+
=
18.
15
1
+
=
19.
15
13
–
=
20.
13
1
+
=
21.
13
5
+
=
22.
13
12
–
=
23.
12
1
+
=
24.
14
12
–
=