solve each system by substitution

1.   x - y +2z = 7
     2x + y + z = 8
     x         -z  = 5

2.   5x - y + z = 4
      x +2y - z = 5
    2x + 3y -3z = 5

so

x=5+z

so

Everytime you see an X, substitute (5+z) in place of the x.

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In the stream of consciousness, there is a river crying:
Living comes much easier, once we admit we're dying.

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x-z=5

so

x=5+z

so

Everytime you see an X, substitute (5+z) in place of the x.

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---

x-z=5

so

x=5+z

so

Everytime you see an X, substitute (5+z) in place of the x.

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And then combine the two resulting equations to get your final variable

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a purpose to human life, no matter who is controlling it,
is to love whoever is around to be loved
- kurt vonnegut