$(7 \mathrm{~A})^{-1}=\left[\begin{array}{ll}4 & 5 \\7 & 8\end{array}\right]$ হলে, A নির্ণয় কর।

$-\frac{1}{21}\left[\begin{array}{rr}-8 & 5 \\7 & -4\end{array}\right]$

$\frac{1}{21}\left[\begin{array}{rr}-8 & 5 \\7 & -4\end{array}\right]$

$\frac{1}{21}\left[\begin{array}{rr}8 & -5 \\-7 & 4\end{array}\right]$

$-\frac{1}{21}\left[\begin{array}{ll}8 & 5 \\7 & 4\end{array}\right]$