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July 7, 2015

July 7, 2015

Posted by **steve** on Saturday, March 8, 2008 at 5:49pm.

x-y-z=8

x-y+2z=17

x is the same in all equations

y is the same in all equations

z is the same in all equations

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**Reiny**, Saturday, March 8, 2008 at 6:14pmAdd the first and the second ---> 2x = 39

x = 19

add the first and the third ----> 2x + 3z = 47

38 + 3z = 47

z = 3

now put those values back into the second

19 - y - 3 = 8

y = 8

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**steve**, Saturday, March 8, 2008 at 6:16pmi am 50 years old, i am sorry but i need this spelled out for me if possible

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**Reiny**, Saturday, March 8, 2008 at 6:43pmWell Steve, I am 68 years old, lol

I assume you are solving these equations?

x + y + z = 30 ---- first equation

x - y - z = 8 -----second equation

2x + 0 + 0 = 38 ---- I added them

x = 19 divided by 2, we now know x

x + y + z = 30 --- first equation again

x - y + 2z = 17 --third equation

2x + 0 + 3z = 47 ---- added them

2x + 3z = 47 , but we know x = 19 so..

38 + 3z = 47

3z = 47 - 38

3z = 9

z = 3 , so now we have x=19 and z=3

let's put this back into the first, or any one really

x + y + z = 30

19 + y + 3 = 30

y + 22 = 30

y = 30-22

y = 8

so x=19, y=8, and z=3

notice those values work in all 3 equations.

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**steve**, Sunday, March 9, 2008 at 11:16amReiny,thanks so much for your help on this!!!!!!!!!!!

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