$\begin{align}  & T\overset{\wedge }{\mathop{W}}\,V+T\overset{\wedge }{\mathop{U}}\,V={{180}^{\circ }}\text{   (opp}\text{. }\angle \text{s of cyclic quad}\text{.)} \\ & \text{8}{{\text{8}}^{\circ }}+{{(3x+20)}^{\circ }}={{180}^{\circ }} \\ & {{108}^{\circ }}+{{(3x)}^{\circ }}={{180}^{\circ }} \\ & 3x={{72}^{\circ }} \\ & x={{24}^{\circ }} \\\end{align}$