Question 614212
Joe has a collection of nickels and dimes that is worth $6.20. If the number of dimes was doubled and the number of nickels was decreased by 7, the value of the coins would be $10.35. How many nickels and dimes does he have?
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let x= number of dimes
let y=number of nickels
===
.10x+.05y=6.20
.10(2x)+.05(y-7)=10.35
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.10x+.05y=6.20
.20x+.05y-.35=10.35
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10x+5y=620
20x+5y=1070
subtract
10x=450
x=45
5y=620-10x=620-450=170
y=170/5=34
ans:
number of dimes=45
number of nickels=34