Is 7 + square root of 5 equal to square root of 5 plus a number, what do you know about the number? Why?

The statement is true. The number is seven. I can find this through the commutative property of addition or plugging in the number and reversing the equation.

Key: a is 7, b is square root of five, c is solution,? is what we're finding

Commutative: a + b = b + a

Plugging and Reversing: a + ? = c, c - a = b