Question 862728
Quarters * 25cents + Dimes * 10cents + Nickels * 5cents = $2.10
0.25Q+0.1D+0.05N=2.1
 
Let D = number of dimes
Let quarters = D/2 <cite> "There are twice as many dimes as quarters" </cite>
Let nickels = D-2 <cite> "...the number of nickels is two less than the number of dimes." </cite>
 
{{{0.25(d/2)+0.1d+0.05(d-2)=2.1}}}
Distribute
{{{d/8+d/10+d/20-1/10=2.1}}}
Add 1/10 to both sides.
{{{d/8+d/10+d/20=2.2}}}
Convert the fractions to 80ths.
{{{10d/80+8d/80+4d/80=2.2}}}
Add the fractions
{{{22d/80=2.2}}}
Multiply both sides by {{{80/22}}}
{{{d=8}}}
There are 8 dimes, 4 quarters, and 6 nickels.