Answer :
Using the properties for similar triangle we know that
[tex]\begin{gathered} \frac{RO}{NL}=\frac{OP}{LM} \\ \frac{RO}{8}=\frac{21}{5} \\ RO=\frac{21\cdot8}{5} \\ RO=\frac{168}{5} \\ RO=33.6 \end{gathered}[/tex]Therefore, RO is equal to 33.6 units.