Question 972938
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Q=number of quarters; N=number of nickels
Q+N=72
Q=72-N Use this to substitute for Q
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$0.25Q+$0.05N=$11.40 Substitute for Q.
$0.25(72-N)+$0.05N=$11.40
$18.00-$0.25N+$0.05N=$11.40
-$0.20N=-$6.60
N=33 They have 33 nickels
Q=72-N=72-33=39 They have 39 quarters
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CHECK:
$0.25Q+$0.05N=$11.40
$0.25(39)+$0.05(33)=$11.40
$9.75+$1.65=$11.40
$11.40=$11.40