What property is 16+31=31+16

The property of 16 + 31 = 31 + 16 is called Commutative Property.

The property states that the order does not matter. This includes both multiplication and addition. Other examples include 4 + 2 = 2 + 4, or even 10 + 9 + 3 = 3 + 9 + 10. In easier words, the problem is just the backwards version of the original problem. 

Commutative Property is your answer

This means that no matter what order it is, the simplified version will still be the same.

hope this helps

I am pretty sure it's Y=2/5x - 4.8. I'm sorry if it's wrong