Question

Jonas wrote 9+8=17 what number sentence shows the commutative property of addition?

Answer 1

9+8=8+9 the trick for commutative is there are two m's in commutative right? well no matter where the mm's are it is still the same word so just like the answer is still the same where ever they go. 

Answer 2

9+8 =8+9
You can rearrange the problem but in addition the answer is always the same.