The correct answer to your question is C. 1/2
So
-4x-5y-z=18
-2x-5y-2z=12
-2x+5y+2z=4
the 2 last equations look perfect for canceling each other so add them together
-2x-5y-2z=12
<u>-2x+5y+2z=4 +</u>
<u />-4x+0y+0z=16
-4x=16
divide both sides by 4
-x=4
multiply -1
x=-4
now we have
-4x-5y-z=18
-2x+5y+2z=4
add them together
-6x+0y+z=22
but x=-4 so
-6(-4)+z=22
24+z=22
subtract 24 from both sides
z =-2
subsitute into any equation
-2x-5y-2z=12
x=-4
z=-2
-2(-4)-5y-2(-2)=12
8-5y+4=12
12-5y=12
subtract 12 from both sides
-5y=0
y=0
x=-4
y=0
z=-2
The answer is c because I checked the math on the paper.
The answer to this is 39 and 27
