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