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