gauss jordan method

Question

Using Gauss-Jordan method to find the solution of the following system of equations, 

 y + z = 4, 

3x + 6y - 3z = 3, 

-2x - 3y + 7z = 10,

Answer 1

0 1 1 4

3 6 -3 3

-2 -3 7 10

r2=r2/3

swap r1 & r2

1 2 -1 1

0 1 1 4

-2 -3 7 10

r3 = r3+2r1

1 2 -1 1

0 1 1 4

0 1 5 12

r3 = r3-r2

1 2 -1 1

0 1 1 4

0 0 4 8

r3 = r3/4

1 2 -1 1

0 1 1 4

0 0 1 2

Reading from bottom up

z = 2

y + 2 = 4 --> y = 2

x +4 -2 = 1 --> x = -1