SOLUTION: Amber has 30 coins in nickles and dimes. In all she has $2.10. How many nickles and dimes does she have.

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Question 158960: Amber has 30 coins in nickles and dimes. In all she has $2.10. How many nickles and dimes does she have.
Found 2 solutions by checkley77, nerdybill:
Answer by checkley77(12844) About Me  (Show Source):
You can put this solution on YOUR website!
N+D=30 OR N=30-D
.05N+.10D=2.10
.05(30-D)+.10D=2.10
1.50-.05D+.10D=2.10
.05D=2.10-1.50
.05D=.60
D=.60/.05
D=12 DIMES.
N+12=30
N=30-12
N=18 NICKLES.
PROOF
.05*18+.10*12=2.10
.90+1.20=2.10
2.10=2.10

Answer by nerdybill(7384) About Me  (Show Source):
You can put this solution on YOUR website!
Amber has 30 coins in nickles and dimes. In all she has $2.10. How many nickles and dimes does she have.
.
Let n = number of nickels
then, because there is a total of 30 coins
30-n = number of dimes
.
Because, we know the total is $2.10
"amt from nickels" + "amt from dimes" = $2.10
.
.05n + .10(30-n) = 2.10
.05n + 3 - .10n = 2.10
3 - .05n = 2.10
3 = .05n+2.10
.90 = .05n
.90/.05 = n
18 = n (number of nickels)
.
number of dimes:
30-n = 30-18 = 12 (number of dimes)