To solve a system of three linear equations in three variables by the addition method.

Solve by the addition method:

x + 3y + z = 6

3x + y - z = -2

2x + 2y - z = 1

x - 2y - z = 1

x + 3y + z = 16

3x - y - z = 12

2y + z = 7

2x - z = 3

x - y = 3

3x + 4z = 5

2y + 3z = 2

2x - 5y = 8

the answers should be (?,?,?) can someone help me break it down??!?