Acube with side length 5h^2is stacked on another cube with side length 3k. what is the total volume of the cubes in factored form?

We know that

The volume of the first cube is
(5h^2)^3
 while
 the volume of the second cube is
 (3k)^3
 so
 their total volume is
(5h^2)^3 + (3k)^3

We can use the special formula for factoring a sum of two cubes:
x^3 + y^3 = (x + y)(x^2 - xy + y^2)
(5h^2)^3 + (3k)^3 = (5h^2 + 3k)((5h^2)^2 - (5h^2)(3k) + (3k)^2)
= (5h^2 + 3k)(25h^4 - 15(h^2)(k) + 9k^2)

the answer is