<PRE><B>Question 825602</B>
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x = boys
y = girls
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x + y = 250
y = 2x - 20
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put the system of linear equations into standard form
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x + y = 250
2x - y = 20
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copy and paste the above linear system in standard form into this matrix-method solver:
https://sooeet.com/math/system-of-linear-equations-solver.php
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solution:
x = boys = 90
y = girls = 160
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system matrix
1 1
2 -1
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inverse of system matrix
0.33333333 0.33333333
0.66666667 -0.33333333
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determinant of system matrix = -3
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Solve and graph linear equations:
https://sooeet.com/math/linear-equation-solver.php
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Solve quadratic equations, quadratic formula:
https://sooeet.com/math/quadratic-formula-solver.php
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Solve systems of linear equations up to 4-equations 4-variables:
https://sooeet.com/math/system-of-linear-equations-solver.php</PRE>