Explanation:
$\begin{array}{*{20}{c}}
{{{\text{C}}_6}{{\text{H}}_5} - {\text{C}}{{\text{H}}_2} - {\text{CH}} - {\text{CH}} - {\text{C}}{{\text{H}}_3}} \\
{\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,|\,\,\,\,\,\,\,\,\,\,\,\,\,\,|} \\
{\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,OH\,\,\,\,\,C{H_3}}
\end{array}$ $\xrightarrow{{{H^ + }}}$ $\begin{array}{*{20}{c}}
{{{\text{C}}_6}{{\text{H}}_5} - {\text{C}}{{\text{H}}_2} - {\text{CH}} - {\text{CH}} - {\text{C}}{{\text{H}}_3}} \\
{\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,|\,\,\,\,\,\,\,\,\,\,\,\,\,\,|} \\
{\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,{\,_ + }O{H_2}\,\,\,\,\,C{H_3}}
\end{array}$ $\to $ $\begin{array}{*{20}{c}}
{{{\text{C}}_6}{{\text{H}}_5} - {\text{C}}{{\text{H}}_2} - \mathop {\text{C}}\limits^ + {\text{H}} - {\text{CH}} - {\text{C}}{{\text{H}}_3}} \\
{\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,|} \\
{\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,C{H_3}}
\end{array}$ $\xrightarrow{{1,2\,\,{H^ + }\,\,shift}}$ $\begin{array}{*{20}{c}}
{{{\text{C}}_6}{{\text{H}}_5} - \mathop {\text{C}}\limits^ + {\text{H}} - C{{\text{H}}_2} - {\text{CH}} - {\text{C}}{{\text{H}}_3}} \\
{\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,|} \\
{\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,C{H_3}}
\end{array}$ $\xrightarrow{\Delta }$ $\begin{array}{*{20}{c}}
{{{\text{C}}_6}{{\text{H}}_5} - C{\text{H}} = C{\text{H}} - {\text{CH}} - {\text{C}}{{\text{H}}_3}} \\
{\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,|} \\
{\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,C{H_3}}
\end{array}$
