The volume of water in the nail =4×3×2.5=30 cubic decimeter.

The amount of water in B is 6× 5× 6 = 180 cubic decimeter.

Total volume of water = 180+30=2 10 cubic decimeter.

The bottom area of the storage tank is A =4×3= 12 square decimeter.

B tank bottom area =6×5=30 square decimeter.

The bottom area ratio is 12:30=2:5.

So let the water in the two tanks be as high as water, and the volume ratio is also 2:5.

So the volume of water in tank A =2 10×2/(2+5)=60 cubic decimeter.

The volume of water in water tank B =2 10-60= 150 cubic decimeter.

A water height =60÷ 12=5 decimeters b water height = 150÷30=5 decimeters.

A: The height of water is 5 decimeters.