SOLUTION: There are 70 quarters and dimes and the total is $14.50. How many quarters and dimes are there?

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Question 562252: There are 70 quarters and dimes and the total is $14.50. How many quarters and dimes are there?
Answer by issacodegard(60) About Me  (Show Source):
You can put this solution on YOUR website!
Hi, let x and y be the number of quarters and dimes respectively.
Then we have two equations from the problem,
x+y=70
(0.25)x+(0.10)y=14.50
So solve this system for the unique solution pair (x,y):
We see that y=70-x, then by substituting we have, (0.25)x+(0.10)(70-x)=14.50
Rearranging, we get (0.15)x=7.50, so x=50 and thus y=20.