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