Correct option is (C) 36
Given that \(x^\circ\) and \(4x^\circ\) are supplementary angles.
\(\therefore\) \(x^\circ+4x^\circ=180^\circ\)
\(\Rightarrow\) \(5x^\circ=180^\circ\)
\(\Rightarrow\) \(x^\circ=\frac{180^\circ}5=36^\circ\)
\(\therefore\) x = 36
