Question 364426
You can list them in order, like, 
[A] is a 2x2 matrix [A]=(1 2 3 4) for [A]={{{(matrix(2,2,1,2,3,4))}}}
[B] is a 3x3 matrix [B]=(9 8 7 6 5 4 3 2 1) for [B]={{{(matrix(3,3,9,8,7,6,5,4,3,2,1))}}}
[C] is a 3x1 matrix [C]=(x y z) for [C]={{{(matrix(3,1,x,y,z))}}}
Then solve,
4[B][C]-12[C]