SOLUTION: There are 21 coins in a jar consisting of quarters nickels and dimes. If there are twice as many dimes as nickels and there is a total of $2.75 in the jar, how many of each coin ar

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Question 1138285: There are 21 coins in a jar consisting of quarters nickels and dimes. If there are twice as many dimes as nickels and there is a total of $2.75 in the jar, how many of each coin are there?
Answer by ikleyn(52794) About Me  (Show Source):
You can put this solution on YOUR website!
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Let N be the number of nickels.

Then the number of dimes is 2N and the number of quarters is (21-N-2N) - (21-3N).


The "money" equation is


    5N + 10*(2N) + 25*(21-3N) = 275  cents.


Simplify and solve


    5N + 20N + 25*21 - 75N = 275


    -50N = 275 - 25*21


      N = %28275+-+25%2A21%29%2F%28-50%29 = 5.


ANSWER.  5 nickel,  2*5 = 10 dimes  and the rest 21 - 5 - 10 = 6 coins are quarters.


CHECK.   5*5 + 10*10 + 6*25 = 275 cents.    ! Correct !