Question 1169633
<pre>
PRICE    QUANTITY SOLD      REVENUE
 120          200
 120+2        200-2
 120+4        200-4
.
.
 120+x        200-x        (120+x)(200-x)
</pre>
R for Revenue,
{{{highlight_green(R=(120+x)(200-x))}}}


Find the zeros of R.  In the exact middle will be the x value for maximum revenue.


120+x=0,...
and then
200-x=0,...
and then find the exact middle value.


Maximum R when x is 40.
This corresponds to price  {{{120+40=160}}} dollar per pair, for maximum revenue of {{{160*(200-40)=180*160=25600}}} dollars.