Question 1097450
{{{5N+10D+25Q=245}}}
{{{N+2D+5Q=49}}}
and
{{{Q=2D}}}
{{{D=Q/2}}}
and
{{{Q=4N}}}
{{{N=Q/4}}}
Substituting,
{{{Q/4+2(Q/2)+5Q=49}}}
{{{Q/4+6Q=49}}}
{{{Q+24Q=196}}}
{{{25Q=196}}}
Does not lead to an integer answer. 
Check the problem setup.
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For 2 nickels, 4 dimes, and 8 quarters, you'd have $2.50.