Answer
$-24500.$
Work Step by Step
Since we have $$\left[\begin{array}{rrr} {40} & {25}&{10} \\ {30} & {5}&{20}\\{15}&{35}&{25}\end{array}\right]=5\left[\begin{array}{rrr} {8} & {5}&{2} \\ {6} & {1}&{4}\\{3}&{7}&{5}\end{array}\right]$$
then, we get
$$\left|\begin{array}{rrr} {40} & {25}&{10} \\ {30} & {5}&{20}\\{15}&{35}&{25}\end{array}\right|=5^3\left|\begin{array}{rrr} {8} & {5}&{2} \\ {6} & {1}&{4}\\{3}&{7}&{5}\end{array}\right|=125(-196)=-24500.$$
