Question

2x-y-z=2
x-5y+3z=-13
-2x-2y+z=-2

Answer 1

u can use cramer's rule here to solve these types of complicated linear equations

Answer 2

best done with matrices as Arnab09 said,
you can substitute z from first and second equation.
and substitute z from first and the last equation.

you will have two equations on x,y from which you can solve fro x and y.