SOLUTION: I have 13 coins in my pocket. They are quarters and dimes and the total dollar amount is $2.05. How many quarters do I have? How many dimes?

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Question 1022559: I have 13 coins in my pocket. They are quarters and dimes and the total dollar amount is $2.05. How many quarters do I have? How many dimes?
Answer by addingup(3677) About Me  (Show Source):
You can put this solution on YOUR website!
q+d = 13 subtract q from both sides:
d = 13-q We'll use this value for d next
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0.25q+0.10d = 2.05 substitute for d
0.25q+0.10(13-q) = 2.05 Multiply
0.25q+1.30-0.10q = 2.05 Subtract q on left and subtract 1.30 on both sides
0.15q = 0.75 divide both sides by 0.15
q = 5 you have 5 quarters and we said that:
d = 13-q = 13-5 = 8 dimes
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Check:
0.25(5)+0.10(8) = 2.05
1.25+0.80 = 2.05 Add on left and you'll see we have the correct answer.
J