Question 1103599: George saves nickels and dimes for tolls. If he has 28 coins worth $2.60, how many are dimes? (Solve using any method of your choice.)
Answer by richwmiller(17219)   (Show Source):
You can put this solution on YOUR website! total count 28
total value $2.60
coins value of $0.05 and $0.10
n +d =28,
0.05*n +0.1*d =2.6
n =28-d
We have two equations with two variables.
We will substitute to make one equation with one variable
0.05*(28-d )+0.1*d =2.6
1.4-0.05d +0.1*d =2.6
0.05*d =1.2
d =24.0
n =28-d
n =4 at $0.05 and d =24 at $0.10
check
4.0+24.0=28
0.05*n +0.1*d =2.6
0.05*4.0+0.1*24.0=2.6
0.2+2.4=2.6
2.6=2.6
ok
Another way
All 28 coins at $0.05 each would bring in $1.40.
The actual total value was $2.60, which is $1.20 more than $1.40.
Each dime is worth $0.05 more than each nickel.
The number of dimes saved was $1.20/$0.05 = 24.
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