SOLUTION: A newspaper carrier has $7.30 in change. He has two more quarters than dimes but three times as many nickels as quarters. How many coins of each type does he have
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Question 825368: A newspaper carrier has $7.30 in change. He has two more quarters than dimes but three times as many nickels as quarters. How many coins of each type does he have Answer by TimothyLamb(4379) (Show Source):
You can put this solution on YOUR website! ---
x = nickels
y = dimes
z = quarters
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z = y + 2
x = 3z
5x + 10y + 25z = 730
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put the system of linear equations into standard form
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y - z = -2
x - 3z = 0
5x + 10y + 25z = 730
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solution:
x = nickels = 45
y = dimes = 13
z = quarters = 15
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system matrix
0 1 -1
1 0 -3
5 10 25
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inverse of system matrix
-0.6 0.7 0.06
0.8 -0.1 0.02
-0.2 -0.1 0.02
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determinant of system matrix = -50
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