What would be the answer?

ANSWER
The equation is used to find out the length of each side of tank is
3,375 = s³
Reason
As given in the question the shape of the tank is cube.
FORMULA
Volume of cube = s³
where s represented the side of a cube.
volume of cube = 3375 cubic feet
put the value in the above equation
we get
3375 = s ³
∛ 3375 = s
Therefore
s = 15 feet
Hence the equation is used to find out the length of the tank is 3,375 = s³
Hence proved