ANSWER:
27
STEP-BY-STEP EXPLANATION:
A matrix is represented by an uppercase letter (A,B, …) and its elements with the same lowercase letter (a,b, …), with a double subscript where the first indicates the row and the second the column a the one that belongs.
Just like that:
Therefore, if we look at the matrix of the statement, we can determine that a2,1 is equal to 27
