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