Question 298233
3x - y - 2z = 11 -- (1)
x – 2y + 3z = 12 -- (2)
x + y - 2z = 5 -- (3)

multiplying (3) by 2 yields 2x + 2y - 4z = 10 then adding this to 2 yields:

3x - z = 22 -- (4)

Then multiplying (1) by 2 yields 6x -2y - 4z = 22 then subtracting it from (2) yields:

5x - 7z = 10 -- (5)

multiplying (4) by 7 yields 21x -7z = 154 and then subtracting it from (5) yields:

16x = 144 --> x = 9 using this in (4), z = 5, using these values in (3), y = 6

So x = 9, y = 6, z = 5