Answer :

[tex]p\% \ of \ \frac{258}{300}= \frac{p}{100}*\frac{258}{300} \\\\ p=\frac{100*258}{300} \\\\ p=\frac{258}{3} \\\\ \boxed{p=86\%}[/tex]
Answer = 86%
Percentages are out of 100...
So to get 300 to 100 you divide by 3...
So divide the 258 by three = 86

Hope this helps! :)