Respuesta :

20^2 + 13.5^2 = c^2
            582.25 = c^2
          √582.25 = c
                 24.1 = c

hope this helps :)
[tex]\bf \textit{pythagorean theorem}\\\\ c^2=a^2+b^2\implies c=\sqrt{a^2+b^2}\qquad \begin{cases} a=20\\ b=13.5 \end{cases} \\\\\\ c=\sqrt{20^2+13.5^2}\implies c=\sqrt{582.25}\implies c\approx 24.12985702402730 \\\\\\ c\approx 24.1\impliedby \textit{rounded up}[/tex]