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I don't know how to solve equations containing three variables

Algebra
Tutor: None Selected Time limit: 1 Day

40=x+y+z

1670=25x+35y+50z

y+2x

Nov 16th, 2014

Hi, the third equation must be y = 2x

Multiply the first equation by 25: 

1000 = 25x + 25y + 25z

Use the second equation subtract the previous one,

 670 = 10y + 25z

Substitute y = 2x into the first equation

40 = 3x +z

  z = 40 - 3x

Substitute again.

670 = 10y + 1000 - 75x

670 = 20x + 1000 - 75x

-330 = -55x

      x = 6

      y =2*6=12

      z = 40-3(6)=22

                                                                                                                                                          


Nov 17th, 2014

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Nov 16th, 2014
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Nov 16th, 2014
Dec 4th, 2016
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