Answer:
-56
Step-by-step explanation:
Formula to get determinant is::
[tex]\left[\begin{array}{ccc}a&b\\c&d\end{array}\right] = ad-bc[/tex]
0(0)-8(7)
0 - 56
-56
[tex]\\ \rm\Rrightarrow \left|\begin{array}{ccc}0 &8 \\ 7& 0\end{array}\right|[/tex]
[tex]\\ \rm\Rrightarrow 0-8(7)[/tex]
[tex]\\ \rm\Rrightarrow 0-56[/tex]
[tex]\\ \rm\Rrightarrow -56[/tex]