SOLUTION: David Bowers collects us gold coins. He has a collection of 47 coins. some are $10 coins, and the rest are $20 coins. If the face value of the coins is $690, how many of each denom

Question 990564: David Bowers collects us gold coins. He has a collection of 47 coins. some are $10 coins, and the rest are $20 coins. If the face value of the coins is $690, how many of each denomination does he have?
Answer by macston(5194) (Show Source): You can put this solution on YOUR website!
.
x=number of $10 coins; y=number of $20 coins
.
x+y=47
x=47-y
.
$10x+$20y=$690
$10(47-y)+$20y=$690
$470-$10y+$20y=$690
$10y=$220
y=22
ANSWER 1: He has twenty two 420 coins.
.
x=47-y=47-22=25
ANSWER 2: He has twenty five $10 coins.
.
CHECK:
$10x+$20y=$690
$10(25)+$20(22)=$690
$250+$440=$690
$690=$690

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