Since a pentagon has 5 sides, the sum of the interior angles of a polygon \(=(5-2) 180^{\circ}=540^{\circ}\)
Then,
\(130^{\circ}+118^{\circ}+80^{\circ}+78^{\circ}+x=540^{\circ}\)
\begin{array}{l}
406^{\circ}+x^{\circ}=540^{\circ} \\
x^{\circ}=540^{\circ}-406^{\circ}=134^{\circ}
\end{array}