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