To add the fractions \(-\frac{8}{14}\) and \(\frac{4}{14}\), you can combine them since they have a common denominator of 14.
\[ -\frac{8}{14} + \frac{4}{14} = \frac{-8 + 4}{14} = \frac{-4}{14} \]
Now, simplify \(\frac{-4}{14}\):
\[ \frac{-4}{14} = \frac{-2}{7} \]
So, the final answer is:
\[ -\frac{2}{7} \]