Question

PLS HELP URGENNT MUST GET 100% on study guide!!!!
If you were to use the substitution method to solve the following system, choose the new system of equations that would result if x was isolated in the second equation.

3x + y + 2z = 1
x + 2y – z = –8
3x – y – 3z = 18

Answer 1

2(2)+(1) : 5x+5y = -15 => x+y=-3
3(2)-(3) : 7y = -42 => y = -6

Answer 2

These are the answer choices. so it would be the 3rd answer?
7y – z = 25
5y – 6z = 42

–5y + 5z = 25
–7y = 42

–5x – 5z = –10
6x – z = 19

7x + 3z = –10
0x – 5z = 19

Answer 3

Sorry, I eliminated z, so none of the equations match.
Here I have eliminated x, with the following:
5y-5z = -25
7y = -42

So that's (B),
I realize the signs have been inverted, but that depends on the order of subtraction. I like to subtract in the direction that gives a positive sign to the variables.