SOLUTION: a coin collection contains nickels dimes quarters there are twice as many dimes as quarters and seven more nickels than dimes the total valve of all the coins is $3.10 how many qua

Question 350987: a coin collection contains nickels dimes quarters there are twice as many dimes as quarters and seven more nickels than dimes the total valve of all the coins is $3.10 how many quarters are in collection
Answer by dabanfield@earthlink.net(8) (Show Source): You can put this solution on YOUR website!
a coin collection contains nickels dimes quarters there are 1.) twice as many dimes as quarters and 2.) seven more nickels than dimes 3.) the total valve of all the coins is $3.10 how many quarters are in collection
Let n be the number of nickels, d the number of dimes and q the number of quarters. From 3) we have:
1.) (5*n) + 10*d + 25*q = 310
We know from 1.) that d = 2*q. From 2.) we know that n = d+7 so n = (2*q) + 7.
Substituting in 1.) we have then:
5*((2*q)+7)) + 10*(2*q) + 25*q = 310
10*q + 35 + 20*q + 25*q = 310
55*q = 310 - 35
55*q = 275
q = 5

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