SOLUTION: mary has $3.75 in nickels, dimes, and quarters. She has three more quarters than dimes. She has twice as many nickels as quarters. How many of each coin does she have?

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Question 252314: mary has $3.75 in nickels, dimes, and quarters. She has three more quarters than dimes. She has twice as many nickels as quarters. How many of each coin does she have?
Answer by drk(1908) About Me  (Show Source):
You can put this solution on YOUR website!
This requires a few equations. First Let N = nickel, D = dime, and Q = quarter. From the first sentence, we get
5N+%2B+10D+%2B+25Q+=+375
This equation is the "value" equation. Notice also I don't use decimal points. Easier to get rid of them I think. Next,
D+%2B+3+=+Q "Three more quarters than dimes".
2Q+=+N+ "Twice as many nickels as quarters}}}
Put all of this together using only Q, we get
5(2Q) + 10(Q-3) + 25Q = 375
Solving for Q, you get Q = 9.
Find the others, N = 18 and D = 6. So we have 18 nickels, 6 dimes, and 9 quarters.