|3a 2z 5m|

|2k 5 6|

I am trying this one but am totally lost. You gave the answer to one earlier. If I am in need of the value of the variables z
Is this answer z=2

Your matrix is not complete. The answer has been given in a different post.

However, bear in mind that when you are given ALL the elements of A, B and C in a matrix equation of
A + B = C,
it is equivalent to being given m x n equations of the form
Aij + Bij = Cij,
where Aij, Bij, Cij represent the elements of row i and column j of the respective matrices. The examples given in the other posts should shed a little more light.