3x3x3/2x2=6.75 decimeter (because the cube is forged into a cuboid, the volume remains unchanged).

2. Rise 1 cm

The formula is (40x25x20+10x10)/(40x25) = 21(/stands for division) 2 1-20= 1 cm.

Because the volume of water in the fish tank can be calculated, and the water rises after falling into the iron block, you have to add the volume of water to the volume of the iron block to get the total volume. If you divide by the area of the fish tank, you will get the current water level, and subtract the original height to get the rising height.

3.500 km

The formula is 9/ 100=0.09 liter, (this is the fuel consumption of a car for one kilometer).

Then use 5x3x3/0.09=500 (the amount of oil is known, divided by the fuel consumption per kilometer, which is the distance to go).

I hope my answer is helpful to you.