Question 1141187
p, total number of pens at the start
<pre>
             RED          BLUE

Initial    {{{3p/5}}}          {{{2p/5}}}

Final      {{{3p/5-260}}}     {{{2p/5-(1/4)(2p/5)}}}

Total    {{{3p/5-260+(2p/5-(1/4)(2p/5))=p/2}}}
</pre>

Solve the TOTAL equation for p.

{{{highlight(p=650)}}}