Final answer:
The volume of the cube is 64x³ + 240x²y + 300xy² + 125y³.
Step-by-step explanation:
The volume of a cube is given by the formula V = s³, where s is the length of one side of the cube.
In this case, the side length of the cube is given as 4x + 5y.
Substituting this expression into the formula for volume, we have V = (4x + 5y)³.
Expanding using the binomial expansion, we get V = 64x³ + 240x²y + 300xy² + 125y³.
Therefore, the volume of the cube is 64x³ + 240x²y + 300xy² + 125y³.