[tex]\bf \boxed{A}\stackrel{x+5}{\rule[0.35em]{10em}{0.25pt}}B\stackrel{2x-11}{\rule[0.35em]{10em}{0.25pt}}\boxed{C} \\\\\\ AB=BC\implies x+5=2x-11\implies 16=x \\\\[-0.35em] ~\dotfill\\\\ \stackrel{AB}{(16)+5}\implies 21~\hspace{10em}\stackrel{\stackrel{\textit{half of AB}}{midpoint}}{10.5}[/tex]
