Lets take a look at how we solve a direct variation problem by writing a proportion and solving it. Remember when you write a proportion, as long as you are consistent with the same variable on top, it will always work. So the general proportion is :

   x1       x2
  -----  =  -----
   y1        y2

However the variables may change and they may have powers on them and numbers with them.


Our first example is fairly straightforward:

If p is directly proportional to q, and p = 9 when q = 7.5, find q when p = 24. Try setting it up as a proportion and then check it below.