SOLUTION: Stefan has a collection of nickels, dimes, and quarters. in all, he has 24 coins. seven of the coins are quarters. the total value of the collection is $2.90. How many nickles and

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: Stefan has a collection of nickels, dimes, and quarters. in all, he has 24 coins. seven of the coins are quarters. the total value of the collection is $2.90. How many nickles and       Log On


   

Question 825611: Stefan has a collection of nickels, dimes, and quarters. in all, he has 24 coins. seven of the coins are quarters. the total value of the collection is $2.90. How many nickles and how many dimes does he have?
Answer by TimothyLamb(4379) About Me  (Show Source):
You can put this solution on YOUR website!
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x + y + z = 24
z = 7
5x + 10y + 25z = 290
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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 nickels = 11
y dimes = 6
z quarters = 7
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system matrix
1 1 1
0 0 1
5 10 25
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inverse of system matrix
2 3 -0.2
-1 -4 0.2
0 1 0
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determinant of system matrix = -5
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