From 1

2x = 21 - 3y - z ---------------4

Put this in 2

21 - 3y -z - 3y +2z = -8

-6y - 3z = -33

2y + z = 11

z = 11 -2y --------------5

Put 5 in 4

2x = 21 - 3y - 11+2y

2x = 10 -y----------------6

Put 5 & 6 in 3

10-y +y - 11 + 2y = 11

2y = 12

y = 6

Put this in 5 & 6

x = 5 - y/2 = 2

z = 11-2y = 11 - 12 = -1

---------------------------------------------------------------

A link that you might like

Adarsh