SOLUTION: 39. A professor is three times as old as one of his pupil, Louis. Four years ago he was four times as old as Louis was at that time. How old is Louis?

Question 926443: 39. A professor is three times as old as one of his pupil, Louis. Four years ago he was four times as old as Louis was at that time. How old is Louis?

Answer by TimothyLamb(4379) (Show Source): You can put this solution on YOUR website!
x = professor age now
y = pupil age now
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x = 3y
x - 4 = 4(y - 4)
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put the system of linear equations into standard form
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x = 3y
x - 4 = 4y - 16
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x - 3y = 0
x - 4y = -12
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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 = professor age now = 36
y = pupil age now = 12
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Solve quadratic equations, quadratic formula:
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Solve systems of linear equations up to 6-equations 6-variables:
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