Explanation:
2A and 2B are scalar multiplications : every item in the matrix has to be multiplied by that factor.
the subtraction then of 2A - 2B is simply to subtract every positive in B from the corresponding same position in A.
that is all.
2A =
4 0
-6 2
2B =
0 2
-4 6
2A - 2B =
4-0 0-2
-6--4 2-6
=
4 -2
-2 -4