Math Problems and Series Completion

Front

6 + 5 =

Back

eleven

Front

3 x 3 =

Back

nine

Front

15 / 3 =

Back

five

Front

4 x 2 =

Back

eight

Front

9 - ? = 5

Back

four

Front

11 + 8 =

Back

nineteen

Front

12 / ? = 3

Back

four

Front

11 - 3 =

Back

eight

Front

20 - ? = 15

Back

five

Front

four - eight - twelve - ? - twenty.

Back

sixteen