Answer
$\det (5A)(2B)=150000$
Work Step by Step
Since $A$ and $B$ are $4 \times 4$ matrix, applying the property $P4$, we obtain:
$\det (5A)=5^4\det (A)=625.5=3125$
and $\det (2B)=2^4\det (B)=16.3=48$
Applying property $P9$:
$\det (5A)(2B)=\det (5A)\det (2B)=3125.48=150000$
