Algebra question

Question

Karla has a collections of nickels dimes and quarters that amount to $10 dollars.  If there are 140 coins and twice as many dimes as quarters find the number of nickels

Answer 1

Let assume that Karla has x nickels, y dimes, z, quarters. Then

 

5x+10y+25z=1000 [1000 cents=$10]

x+y+z=140

y=2z

 

5x+20z+25z=1000

x+2z+z=140

 

5x+45z=1000

x+3z=140

 

x+9z=200

x+3z=140

 

6z=60

z=10

y=20

x=110

 

So Karla has 110 nickels, 20 dimes and 10 quarters.

 

 

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