Question 788218
x + y + z = -2
3x + 2y + z = 9
y - z/2 = 10 ----> 2y - z = 20


Eliminate the variable z.


equation 2 and equation 3:
3x + 2y + z = 9
2y - z = 20
-----------------------
3x + 4y = 29


equation 1 and equation 3:
x + y + z = -2
2y - z = 20
---------------------
x + 3y = 18


Use any method (elimination, substitution, etc) to solve for x and y. Then, substitute those values to solve for z.