SOLUTION: Mary has 84 coins that have a total value of 5.55$. if all the coins are nickels and dimes. How many of each does mary have?

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Question 126959: Mary has 84 coins that have a total value of 5.55$. if all the coins are nickels and dimes. How many of each does mary have?
Answer by checkley71(8403) About Me  (Show Source):
You can put this solution on YOUR website!
D+N=84 OR D=84-N
.10D+.05N=5.55
.10(84-N)+.05N=555.
8.4-.10N+.05N=5.55
-.05N=5.55-8.4
-.05N-2.85
N=-2.85/.05
N=57 IS THE NUMBER OF NICLELS.
D+57=84
D=84-57
D=27 IS THE NUMBER OF DIMES.
proof:
.10*27=.05*57=5.55
2.70+2.85=5.55
5.55=5.55