What would be the height of water in a tank if the tank contains 81000 cm cubed of water with length 60 cm width 45 cm and height 70 cm?

Assuming the tank is cuboid, the area of its base is 60 x 40 cm squared, i.e. 2400 cm squared.

Thus the height of water is 81000/2400 cm = 33.75 cm.