Question 352519
Let q = # of quarters, n = # of nickels.
Then from the given, {{{q+n=18}}}, and {{{0.25q+0.05n=2.30}}}
From the first equation, {{{q=18-n}}}.
Substituting this into the second equation gives
{{{0.25*(18-n)+0.05n=2.30}}}
{{{4.5-0.25n+0.05n=2.30}}}
{{{-0.2n=-2.2}}}
{{{n=(-2.2)/(-0.2)}}}
{{{n=11}}}
This gives {{{q=18-11=7}}}
Therefore there are 11 nickels and 7 quarters.