Is relative frequency over the total or just the total of the subset?
For example if 79 boys get bullied and the total number of students including girls is 200, and the total number of boys are 103 do I divide by 200 or 103?
You would need some way of qualifying this group of boys. 79/103 is the PROPORTION of boys bullied, and 79/200 is the proportion of individuals in the school bullied who are boys.
A frequency chart would have some "class" to it - the only "class" you have is boy/girl - neither of which works for a frequency distribution.
Now if you had them broken up by grades, then you could work something out. What does the original problem say?