Question 1041663
I think you mean that x is the width of the poster.
Let y be the length of the poster.
So the total area of the poster would be,
{{{A=xy}}}
{{{xy=500}}}
{{{y=500/x}}}
With the two inch margin, the printed width becomes,
{{{x[p]=x-2-2=x-4}}}
The printed length becomes,
{{{y[p]=y-2-4=y-6}}}
So the printed area would be,
{{{A[p]=x[p]*y[p]}}}
{{{A[p]=(x-4)(y-6)}}}
Substituting,
{{{A[p]=(x-4)(500/x-6)}}}