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