The formula of a volume of a cube:

We have 
Substitute:
![a^3=474.552\to a=\sqrt[3]{474.552}\\\\a=7.8\ m](https://tex.z-dn.net/?f=a%5E3%3D474.552%5Cto%20a%3D%5Csqrt%5B3%5D%7B474.552%7D%5C%5C%5C%5Ca%3D7.8%5C%20m)
Answer: The length of each side of the box is equal 7.8 m.
The first option is

The second option is

So, neither of them is equivalent to 
He needed to divide instead of subtracting it on the last step.
Answer:
The correct answer is Never