Answer:
about 10.924 inches
Step-by-step explanation:
If all of the dimensions are equal, the box is a cube. Its side length is the cube root of the volume.
V = s³
s = ∛V = ∛1300 ≈ 10.913929 . . . . inches
I can't see images.
Can you tell me what is looks like?
The equation has to (or be transformed to) contain one object in the left side and the other object at the right side multiplied by a constant, without an independent term.

this formula is used to determine gpm (gallons per minute) of flow with a known hose diameter (d) and nozzle pressure (np). The constant (29.7) is consistent when figuring flow with in gallons with a know pressure expressed in psi (pounds per square inch).
Scenario example: a firefighter is using a handline to fight fire with an 1 3/4 inch line with a nozzle pressure of 100 psi. How much water is the firefighter flowing when fighting fire?