Respuesta :

[tex]\begin{gathered} \text{There are 6 numbers in the series, So} \\ \operatorname{median}\text{ =}\frac{21+x}{2} \\ 28.5=\frac{21+x}{2} \\ 28.5\times2=21+x \\ 21+x=57 \\ x=57-21 \\ x=36 \end{gathered}[/tex]