# algebra

posted by on .

x+y+z=30
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

• algebra - ,

Add 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

• algebra - ,

i am 50 years old, i am sorry but i need this spelled out for me if possible

• algebra - ,

Well 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.

• algebra - ,

Reiny,thanks so much for your help on this!!!!!!!!!!!

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