Please solve the 7th question.
Please do not provide any link.
Q.7. A rectangular tank 30 cm $\times$ 20 cm $\times$ 12 cm contains water to a depth of 6 cm. A metal cube of side 10 cm is placed in the tank with its one face resting on the bottom of the tank. Find the volume of water, in litres, that must be poured in the tank so that the metal cube is just submerged in the water.