A box of 80 coins, consisting of only nickels and dimes, is worth 7 dollars and 80 cents. Find the number of nickels.

Question

Mathematics

Queen

11 May, 10:52

A box of 80 coins, consisting of only nickels and dimes, is worth 7 dollars and 80 cents. Find the number of nickels.

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Answers (1)

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Maryjane · Answer 1

4 nickles

Explanation:

80=N+D

7.80=0.05N + 0.1D

D=80-N

7.80=0.05N + 0.1 (80-N)

7.80=0.05N + 8 - 0.1N

0.1N + 7.80 = 8 + 0.05N

0.05N = 8-7.80

0.05N = 0.2

N = 4