Notice that:

6 + 5 = 11    and    5 + 6 = 11

7 + 2 = 9    and    2 + 7 = 9

8 + 13 = 21    and    13 + 8 = 21

28 + 59 = 87    and    59 + 28 = 87

Adding can be done in any order. 

You always get the same answer.

*****WARNING*****

Subtracting is different.

28 - 19 = 9    but    19 - 28 = -9

They are not the same.

Subtracting cannot be done in any order.

Does that make sense?

Let's try some questions now.