Chapter P - Section P.1 - Algebraic Expressions, Mathematical Models, and Real Numbers - Exercise Set - Page 18: 84

Inverse property of addition

The inverse property of addition states that The sum of a real number and its additive inverse gives 0, the additive identity. This problem illustrates that concept because a real number, $x+4$ is added to its additive inverse, $-(x+4)$, and it is shown that the sum is equal to 0.