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Krishaun has $5, $10, and $20 coins worth a total of $560. She has the same number of $5 coins as $10 coins, and the same number of $10 coins as $20 coins. How many $20 coins does Krishaun have?a.16
b.15
c.20
d.28
e.17

 Jul 6, 2021
 #1
avatar+33621 
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f = t = n          five   ten and twenty

 

5n  +   10n  + 20n  = 560

35n = 560

n = twenty dollar coins = 16

 Jul 6, 2021
 #2
avatar+234 
+1

Let's make the number of 5 coins 'a', number of 10 coins 'b', and the number of 20 coins 'c'. Writing as an equation we get,

\(5a+10b+20c=560\)

\(a+2b+4c=112\)

We also know that she has the same amount of all coins, so we can replace a, b, c, with a common variable of 'x'.

\(x+2x+4x=112\)

\(x = 16\)

Because x  is equal to the amount of each of the coins, she has 16 $20 coins.

 Jul 6, 2021

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