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