I dunno if this is right or not but x=20.
I think its the second one
Add the last two equations to eliminate <em>x</em> :
(<em>x</em> - 2<em>y</em> - 3<em>z</em>) + (- <em>x</em> + <em>y</em> + 2<em>z</em>) = 0 + 3
- <em>y</em> - <em>z</em> = 3
<em>y</em> + <em>z</em> = -3
Subtract this from the first equation to eliminate <em>z</em>, then solve for <em>y</em> :
(2<em>y</em> + <em>z</em>) - (<em>y</em> + <em>z</em>) = -8 - (-3)
<em>y</em> = -5
Plug this into the first equation to solve for <em>z</em> :
2(-5) + <em>z</em> = -8
<em>z</em> = 2
Plug both of these into either the second or third equations to solve for <em>x</em> :
<em>x</em> - 2(-5) - 3(2) = 0
<em>x</em> = -4
Answer:
x=11
Step-by-step explanation:
7x-9-4(x-1)=28
7x-9-4x+4=28
3x-5=28
3x=33
x=11