SOLUTION: I need some help with this problem: Justin has $6.50 in quarters, dimes, and nickels. If he has a total of 42 coins and he has twice as many dimes as nickels, how many of each coin

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Question 838753: I need some help with this problem: Justin has $6.50 in quarters, dimes, and nickels. If he has a total of 42 coins and he has twice as many dimes as nickels, how many of each coin does he have?
I think that I have the right equations, but everytime I try to solve, the answers either don't make sense or are wrong.
The equations I know are:
n+d+q=42 and 5n+10d+25q=650
The equation that I'm not sure about is the part in the problem where is says he has twice as many dimes as nickles. I've tried 2d-n=0 and then I solved for n which gave me: n=2d, but like I said, none of the answers I get when I try to solve make sense or are right.
Please help!
Answer by ewatrrr(24785)   (Show Source): You can put this solution on YOUR website!
 

Hi

n+d+q=42 

he has twice as many dimes as nickels

nickels:  x

dimes:  2x

quarters  (42-2x - x)  0r (42-3x)

5n+10d+25q=650  |Yes! CENTS make sense. Good work.

 5x + 10(2x) + 25(42-3x) = 650¢  *** |Solving for x

 5x + 20x + 1050 - 75x = 650

          -50x =  -400

             x = 8, number oF Nickels. 16 Dimes and 18 Quarters (42-24)

CHECKING our answer***

 40 + 160 + 25*18 = 40 + 160 + 450 = 650¢  0r $6.50

Wish You the Best in your Studies.



 

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