Question 714506
In story problems like this, the word "is" can be replaced by an equal sign, and the work "of" can be replaced by multiplication.  And finally "%" translates to "divided by 100"
 
You've already done most of the work by stating "24 is 12% of x"  All we need to do is translate that into an equation:
 
24 is(=) 12%(/100) of(*) x
 
{{{24 = (12/100)*x}}}
 
{{{(100/12)*24 = (100/12)*(12/100)*x}}}
 
{{{2400/12 = (1200/1200)*x}}}
 
{{{200 = 1*x}}}
 
{{{x = 200}}}
 
So there are 200 6th graders at the school.