SOLUTION: a bag contains 18 coins consisting of quarters and dimes. The total value of the coins is $2.85. Which system of equations can be used to determine the number of quarters, q, and t

Question 1066634: a bag contains 18 coins consisting of quarters and dimes. The total value of the coins is $2.85. Which system of equations can be used to determine the number of quarters, q, and the number of dimes, d, in the bag?
Answer by addingup(3677) (Show Source): You can put this solution on YOUR website!
q+d = 18 subtract d from both sides:
q = 18-d
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0.25q+0.10d = 2.85 substitute for q:
0.25(18-d)+0.10d = 2.85
4.5-0.25d+0.10d = 2.85
-0.15d = -1.65
d = 11
and
q = 18-11 = 7
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Check:
11*0.10 = 1.10
7*0.25 = 1.75
total = 2.85 Correct
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