solve by elimination ( step by step )

Question

-4x - 5y - z = 18

-2x -5y -2z = 12

-2x + 5y + 2z = 4

Answer 1

Add the 3rd equation to the first to the 2nd..

This will eliminate both the y and z variables!

Use the value you get for x in the first 2 equations to give you a pair in y and z

Subtract one of these equations from the other; this will eliminate the y variable.

Then use the x and y results to determine z.

Messy...but not the worst mess you can get with 3x3 systems!