Answer:
x=7/13, y=19/13, z=74/13
Explanation:
Add or subtract multiples of equations to eliminate one variable. I picked z to eliminate.
Subtract the 1st equation from the 2nd equation.
2x + 2Y = 4 or x + y = 2 or y = -x + 2, then
Multiple the 2nd equation by 2 and subtract the 3rd equation.
9x - 4y = 5 then sub (-x + 2) for y from previous step.
9x - 4(-x +2) = 5
13x -2 = 5
13x = 7
x = 7/13
plug that into either of the step 1 equations to gey y.
y = -x + 2
y = -7/13 + 2
y = 19/13
then plug the found x and y into any one of the original equations to get z.
-x + 2y - 2z = -9
-7/13 + 2(19/13) - 2z = -9
31/13 - 2z = -9
-2z = -9 - 31/13
-2z = -117/13 - 31/13 = -148/13
z = 74/13