Question 946396
q, how many pencils bought at R7.20; this price is {{{7.20/q}}} R's per pencil.


Reader might assume that "c" means 0.01 of 1 R.  The stated condition may mean price becomes {{{7.20/q+4/100}}}  R's per pencil.  Now, R7.20 will allow purchase of q-6 pencils.


What is the hypothetical new purchase?
{{{(q-6)/(7.20/q+4/100)=7.20}}}


Check carefully how that equation works.  Examine the units.
Number of pencils DIVIDED BY price per pencil, IS the purchase cost.
When that makes sense, then solve the equation for q.