The left term is (5x)³.
The right term is 10³.
So, you can use the formula for the factorization of the difference of cubes.
... a³ - b³ = (a-b)(a² +ab +b²)
Here, you have a=5x, b=10, so the factorization is
... 125x³ -1000 = (5x-10)(25x² +50x +100)
