Question 574161: a collection of dimes and quarters is worth $16.20. there are 81 coins in all. how many dimes and how many quarters? Answer by Maths68(1474) (Show Source):
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Let
Quarters=x
Dimes=81-x
Total Coins=81
Value of a Quarter = $0.25
Value of a Dime = $0.10
Total value of all coins = $16.20
(Value of a Quarter)(Quarters)+(Value of a Dimes)(Dimes)= Total value of all coins
(0.25)(x)+(0.10)(81-x)=16.20
0.25x+8.1-0.10x=16.20
0.25x-0.10x=16.20-8.10
0.15x=8.1
0.15x/0.15=8.1/0.15
x=54
Quarters=x=54
Dimes=81-x=81-54=27
Check
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Total Quarters*value of a Quarter+Total Dimes*value of a Dime = Total Amount
54*0.25+27*0.1=16.20
13.5+2.7=16.20
16.20=16.20
