SOLUTION: A wallet contains 10 coins, all nickels or dimes, totaling 80 cents. How many dimes are there?

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Question 242339: A wallet contains 10 coins, all nickels or dimes, totaling 80 cents. How many
dimes are there?
Answer by checkley77(12844) About Me  (Show Source):
You can put this solution on YOUR website!
N+D=10 OR N=10-D
.05N+.10D=.80
.05(10-D)+.10D=.80
.5-.05D+.10D=.80
.05D=.80-.50
.05D=.30
D=.30/.05
D=6 DIMES.
10-6=4 NICKELS.
PROOF:
.05*4+.10*6=.80
.20+.60=.80
.80=.80