Question 14263
First set up an equation

{{{3/4=240}}}
Then in order to find out the total amount of students, we need a variable. Plug it next to the fraction. 

{{{3/4x=240}}}
Then get rid of the {{{3/4}}} by multiplying it by its recipricol (flip the fraction upside-down) 
You should get {{{X=240*(4/3)}}}
Then solve.  
{{{X=320}}}