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