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