Question 989693
q quarters and d dimes;
{{{0.25q+0.1d=2.80}}}
{{{5q+2d=56}}}



Friend says,  {{{q=8+d}}}.
Check how this is.
{{{5(8+d)+2d=56}}}
{{{40+5d+2d=56}}}
{{{7d=56-40}}}
{{{7d=16}}}
{{{d=16/7}}}-----------NOT a whole number.


The friend is wrong.  The idea leads to d number of dimes being nonwhole.