Question

How to find out the values of x,y,z and w

Answer 1

In the question , it is clear that 
x = 3           ......................................         1
3x - y = 2    ......................................         2
⇒ 9 -y=2
⇒y = 7
2x+z=4       ......................................         3
⇒ 6 + z = 4
⇒z = -2
3y-w=7       ......................................         4
⇒ w = 21 - 7 = 14
Hence ,
x = 3
y = 7
z = -2
w = 14
I hope my answer is correct 
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Answer 2

x = 3
y = 7
z = -2
w = 14