Question 314177
Let N be the number of nickels, Q the number of quarters.
1.{{{N=4+Q}}}
2.{{{5N+25Q=230}}}
Multiply eq. 1 by (-5) and add to eq. 2,
{{{-5N+5N+25Q=-20-5Q+230}}}
{{{25Q=-5Q+210}}}
{{{30Q=210}}}
{{{highlight( Q=7)}}}
Then from eq. 1,
{{{N=4+Q}}}
{{{N=4+7}}}
{{{highlight( N=11)}}}