Question 927031: 120 quarters and dimes worth $18.75
How many of each coin does he have?
Answer by TimothyLamb(4379)   (Show Source):
You can put this solution on YOUR website! x = dimes
y = quarters
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x + y = 120
10x + 25y = 1875
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put the system of linear equations into standard form
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x + y = 120
10x + 25y = 1875
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copy and paste the above standard form linear equations in to this solver:
https://sooeet.com/math/system-of-linear-equations-solver.php
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solution:
x = dimes = 75
y = quarters = 45
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now by elimination:
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-25(x + y = 120)
10x + 25y = 1875
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-25x - 25y = -25*120
10x + 25y = 1875
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add the two equations:
-15x = -25*120 + 1875
x = (-25*120 + 1875)/-15
x = 75
y = 120 - x
y = 120 - 75
y = 45
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solution by elimination:
x = dimes = 75
y = quarters = 45
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