The first step is to calculate how many cubic decimeters of water flow in 3.5 minutes. Then the second step is to add 4400 to the formula because water needs to add the volume of rockery, that is, if the object is placed in a cylindrical container filled with water, the meaning is the same. The third step is to calculate the bottom area of the fish tank. Then divide the volume by the bottom area to calculate the height ~ ~

I wish you progress in your study ~ ~ ~ ~ ~ Hope to adopt it. .