#### Answer

$-\frac{7}{8}$

#### Work Step by Step

The additive inverse is the opposite of a number. The sum of a number and its additive inverse is 0.
Therefore, the additive inverse of $\frac{7}{8}$ is $-(\frac{7}{8})=-\frac{7}{8}$.
We can check to make sure the sum of these two numbers is 0.
$-\frac{7}{8}+\frac{7}{8}=\frac{7}{8}-\frac{7}{8}=0$