Solution
= Solution
The two-by-two <determinant> is the difference of the diagonal products:
$$
\boxed{\begin{vmatrix}8&1\\5&3\end{vmatrix}=8\cdot3-1\cdot5=19.}
$$
= Solution
The two-by-two <determinant> is the difference of the diagonal products:
$$
\boxed{\begin{vmatrix}8&1\\5&3\end{vmatrix}=8\cdot3-1\cdot5=19.}
$$