adding within 20

Front

3 + 12 =

Back

15

Front

12 + 8 =

Back

20

Front

7 + 9 =

Back

16

Front

8 + 7 =

Back

15

Front

5 + 6 =

Back

11

Front

1 + 1 =

Back

2

Front

2 + 2 =

Back

4

Front

4 + 5 =

Back

9

Front

10 + 5 =

Back

15

Front

6 + 3 =

Back

9