Explanation:
\({{\text{C}}{{\text{H}}_3}{\text{C}}{{\text{H}}_2}{\text{COOH}}}\) \({\xrightarrow{{\operatorname{Re} d{\kern 1pt} P{\kern 1pt} + {\kern 1pt} B{r_2}}}}\) $\begin{array}{*{20}{c}}
{Br\,\,\,\,\,\,\,} \\
{|\,\,\,\,\,\,\,\,\,\,} \\
{C{H_3} - CH - COOH}
\end{array}$ ${\xrightarrow[\Delta ]{{{\text{Alc}}{\text{.KOH}}}}{\text{C}}{{\text{H}}_2}{\text{ = CH}}{\mkern 1mu} {\text{ - }}{\mkern 1mu} {\text{COOH}}}$