Seudónimo Seudónimo
  • 12-01-2017
  • Mathematics
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a collection of quarters and nickels is worth 13.50. there are 78 coins in all. find the number of each coin

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apologiabiology
apologiabiology apologiabiology
  • 12-01-2017
q+n=78
25q+5n=1350
divide 2nd equation by 5
5q+n=270

q+n=78
5q+n=270
mulitply first equaton by -1 and add to 2nd

-q-n=-78
5q+n=270 +
4q+0n=192

4q=192
divide both sides by 4
q=48

sub back

q+n=78
48+n=78
minus 48 both sides
n=30

30 nickles
48 quarters
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