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