SOLUTION: a pile of 68 coins consists of quarters and dimes. if the value of the pile is 15.05, how many dimes are there?

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Question 698340: a pile of 68 coins consists of quarters and dimes. if the value of the pile is 15.05, how many dimes are there?
Answer by Stitch(470) About Me  (Show Source):
You can put this solution on YOUR website!
Let A = # of Quarters
Let B = # of Dimes
Equation 1: A+%2B+B+=+68%29%0D%0AEquation+2%3A+%7B%7B%7B0.25A+%2B+0.1B+=+15.05
Solve equation 1 for one of the variables
Equation 1: A+%2B+B+=+68%29%0D%0A%7B%7B%7BA+=+68+-+B
Plug (68 - B) into equation 2 for A
Equation 2: 0.25A+%2B+0.1B+=+15.05
0.25%2A%2868+-+B%29+%2B+0.1B+=+15.05
Simplify
17+-+0.25B+%2B+0.1B+=+15.05
Combine like terms
17+-+0.15B+=+15.05
Subtract 17 from both sides
-0.15B+=+-1.95
Divide both sides by -0.15
highlight%28B+=+13%29
Now plug 13 into equation 1 for B
Equation 1: A+%2B+B+=+68%29%0D%0A%7B%7B%7BA+%2B+%2813%29+=+68
Subtract 13 from both sides
highlight_green%28A+=+55%29
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There are 13 dimes