SOLUTION: charlie's piggy bank was filled with dimes and nickels. he took the money out and counted a total of 419 coins. the coins were worth $36.05. how many nickels were in the piggy bank

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Question 273238: charlie's piggy bank was filled with dimes and nickels. he took the money out and counted a total of 419 coins. the coins were worth $36.05. how many nickels were in the piggy bank?
Answer by CharlesG2(834) About Me  (Show Source):
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charlie's piggy bank was filled with dimes and nickels. he took the money out and counted a total of 419 coins. the coins were worth $36.05. how many nickels were in the piggy bank?
D + N = 419 (multiply by -0.10)
0.10D + 0.05N = 36.05
-0.10D - 0.10N = -41.9
0.10D + 0.05N = 36.05 (add the top one)
-0.10D - 0.10N = -41.9
0D - 0.05N = -5.85 (solve this one for N)
N = -5.85 / -0.05 = 585/5 = 117 mickels
419 - 117 = 302 dimes = D
0.10(302) + 0.05(117) = 30.2 + 5.85 = 30 + 6.05 = 36.05 (added 0.2 to 5.85 then added)