Answer
See below.
Work Step by Step
$\begin{vmatrix} a_{11} & a_{12} \\ a_{21} & a_{22} \end{vmatrix}\begin{vmatrix} 1 & 0 \\ 0 & 1 \end{vmatrix}=\begin{vmatrix} a_{11} & a_{12} \\ a_{21} & a_{22} \end{vmatrix}$, thus the elements of the first matrix remain the same (because they are multiplied with the identity matrix.
