SOLUTION: Sam has 30 nickels and dimes worth $2.40. How many nickels does he have?

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Question 299071: Sam has 30 nickels and dimes worth $2.40. How many nickels does he have?
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=2.40
.05(30-D)+.10D=2.40
1.5-.05D+.10D=2.40
.05D=2.40-1.5
.05D=.90
D=.90/.05
D=18 NUMBER OF DIMES.
N=30-18
N=12 NUMBER OF NICKELS.
PROOF:
.05*12+.10*18=2.40
.60+1.80=2.40
2.40=2.40