Question 895738
The count of each coin assigned variables n,d, q.


{{{0.05n+0.1d+0.25q=5}}}, accounts for dollar money quantity and should be simplified;
{{{n+2d+5q=100}}}.


{{{n/d=3}}} according to description, so {{{n=3d}}}.


{{{0.25q/(0.05n)=5}}} according to description, so {{{5q/n=5}}}, {{{q/n=1}}} meaning {{{q=n}}}.


System to solve is this:

{{{highlight_green(system(n+2d+5q=100,n=3d,q=n))}}}


More than one solution path you can take.


Substitute for n:
{{{q+2d+5q=100}}}
{{{2d+6q=100}}}
{{{d+3q=50}}}
-
{{{q=3d}}}, when substitute for n in the second equation of the listed system.


System now after eliminating n is:
{{{highlight(system(d+3q=50,q=3d))}}}


Continuing,
{{{d+3(3d)=50}}}
{{{d+9d=50}}}
{{{10d=50}}}
{{{highlight(d=5)}}}


You can work through the other equations to solve for n and q.



--

n=15, and therefore q=15.