Question 830811
Joe received {{{(5/7)}}} of the value that he planned to have.


Let d = the value of the Compact Disc.
-
{{{(5/7)(22+d)=14+d}}}
The fraction of what Joe believed he would receive is the right-hand member.  The two members appear different but are the same value.


{{{5(22+d)=7(14+d)}}}
{{{5*22+5d=7*14+7d}}}
{{{5*22-7*14=7d-5d}}}
{{{2(5*11-7*7)=2d}}}
{{{2(55-49)=2d}}}
{{{55-49=d}}}
{{{highlight(d=6)}}}