If $A$ and $B$ are $4\times 4$ matrices, and $\det(A)=3$, $\det(B)=5$, find the $\det$ of the following

Question

$|(3A)^{-1}| = \dfrac{1}{|(3A)|} = \dfrac{1}{3^4\cdot 3} = \dfrac{1}{243}$

$|3(B^{-1})| = \dfrac{3^4}{|B|} = \dfrac{81}{5}$

$|(2A)B^{-1}| = |(2A)|B^{-1}|=\dfrac{2^4\cdot|A|}{|B|} = \dfrac{2^4 \cdot 3}{5} = \dfrac{48}{5}$

$|(\dfrac{1}{5}B)A| = |(\dfrac{1}{5}B)|A| = {(\dfrac{1}{5})^4\cdot|B|\cdot|A|} = \dfrac{1 \cdot 5 \cdot 3}{625} = \dfrac{15}{625}$

$|(3A^{-1})| = \dfrac{3^4}{|A|} = \dfrac{81}{3}$

I just want to know if I have messed up anywhere, or if all the determinants are correct please.