Oefen erbijsommen en erafsommen tot 50
In de mix
1.
25
10
+
=
2.
20
15
–
=
3.
15
15
+
=
4.
25
20
+
=
5.
40
30
–
=
6.
20
5
+
=
7.
40
15
–
=
8.
40
15
–
=
9.
25
20
–
=
10.
25
15
–
=
11.
35
15
–
=
12.
20
5
+
=
13.
20
20
+
=
14.
25
20
–
=
15.
10
5
+
=
16.
15
10
+
=
17.
15
30
+
=
18.
20
10
+
=
19.
25
20
–
=
20.
20
15
–
=
21.
15
5
+
=
22.
25
5
+
=
23.
20
25
+
=
24.
25
15
–
=