Question 837066
n nickels
q quarters

{{{n=q+15}}}, "fifteen more nickels than quarters";
{{{0.05n+0.25q=5.25}}}


Multiply the money count equation by 20.
{{{n+5q=105}}}


SYSTEM TO SOLVE:
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n-q=15
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n+5q=105
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Conveniently suited to Elimination Method.
{{{(n+5q)-(n-q)=105-15}}}
{{{6q=90}}}
{{{q=90/6=(3*3*2*5)/(2*3)}}}
{{{highlight(q=15)}}}
-
{{{n-q=15}}}
{{{n=15+q}}}
{{{n=15+15}}}
{{{highlight(n=30)}}}