SOLUTION: I have 20 coins consisting of nickels and dimes. Their total value is $1.30. How many are nickels and how many are dimes. I need two equations so I can do systems of equations

Question 1009646: I have 20 coins consisting of nickels and dimes. Their total value is $1.30. How many are nickels and how many are dimes. I need two equations so I can do systems of equations
Found 2 solutions by macston, stanbon:
Answer by macston(5194) (Show Source): You can put this solution on YOUR website!
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N=number of nickels; D=number of dimes
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N+D=20
N=20-D
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$0.05N+$0.10D=$1.30 Substitute for N from above.
$0.05(20-D)+$0.10D=$1.30
$1.00-$0.05D+$0.10D=$1.30
$0.05D=$0.30
D=6
ANSWER 1: There are 6 dimes.
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N=20-D=20-6=14
ANSWER 2: There are 14 nickels.
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CHECK:
$0.05N+$0.10D=$1.30
$0.05(14)+$0.10(6)=$1.30
$0.70+$0.60=$1.30
$1.30=$1.30
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Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
I have 20 coins consisting of nickels and dimes. Their total value is $1.30. How many are nickels and how many are dimes. I need two equations so I can do systems of equations
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Quantity Eq:: n + d = 20 coins
Value Eq:::: 5n +10d = 130 cents
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Modify the Value Eq for elimination of one of the variables::
n + d = 20
n + 2d = 26
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Subtract and solve for "d"::
d = 6 (# of dimes)
n = 20-6 = 14 (# of nickels)
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Cheers,
Stan H.
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