Answer
The number of dimes: 13
The number of nickels: 8
Work Step by Step
Let n = the amount of nickels
and d = the amount of dimes.
There are 21 coins and the total value is $\$1.70$. Thus we have the system:
$n+d=21 \rightarrow n=21 - d$
$0.05n+0.10d=1.7$
Substitute $n=21 - d$ in the second equation.
$0.05(21-d)+0.10d=1.7$
$1.05-0.05d+0.10d=1.7$
$0.05d=0.65$
$d=13$
$n=21 - d \rightarrow n=21-13=8$
The number of dimes: 13
The number of nickels: 8
