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