Chapter 2 - Solving Equations - 2-4 Solving Equations With Variables on Both Sides - Practice and Problem-Solving Exercises - Page 106: 32

This is an identity.

$4-d=-(d-4) \\\\ 4-d=4-d$ We first use the distributive property on both sides of the equation to simplify. This leaves us with the same thing on both sides of the equation, so this is an identity. An identity is an equation that is true for every possible value.