Question 1119320
{{{system(n+d+q=180,2d=n+q,0.05n+0.1d+0.25q=16)}}}


{{{system(n+q+d=180,n+q-2d=0,n+2d+5q=320)}}}



Just this part of that system allows to eliminate two variables at once to find d.
{{{system((n+q)+d=180,(n+q)-2d=0)}}}


{{{3d=180}}}


{{{highlight(d=60)}}}


This also means {{{2d=120=n+q}}}


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{{{highlight(q=20)}}}


and from {{{n+q=120}}}

{{{n=120-q}}}

{{{n=120-20}}}

{{{highlight(n=100)}}}