Question 256454
The assumption is that the equation is
{{{2w+x-4y+3z= 20}}}
.
.
.
The determinant of the matrix is 74.
The inverse matrix is 
[A]inv={{{(1/74)*(
 matrix( 4, 4, 
45, 8, 9, 14,
24,24,-10,42,
39,2,-7,22, 
14,14,-12,6))}}}
and the solution set [X] is, 
   [X]={{{(1/74)*(
 matrix( 4, 1, 
354,26,70,342))}}}
(w,x,y,z)=(354/74,26/74,70/74,342/74)
NOTE : The answer is not in simplest terms.