Below I used mt = A + B
mt = Array[Subscript[m, ##] &, {3, 3}];
ct = Array[Subscript[c, ##] &, {3, 3}];
yv = Array[Subscript[y, ##] &, 3];
Simplify[Inverse[mt].ct.yv] // MatrixForm
Without further restrictions thisis what you can get. If you want to assign values to matrix elemehnt syou may use
Thread[Flatten[mt] -> Range[9]]
( Range[9] is here a substitute for the list of your specific values). Of course the same applies to matrix ct.
