Homemade Extension Board from waste Cardboard

The given figure shows a square piece of carboard of side 10 inches. A rectangular piece of dimensions 3 inches times 2 inches is cut from the cardboard as shown in the figure. Area of the remaining portion of the cardboard is

In Hydra, waste material of food digestion and nitrogenous waste material are removed from

In Planaria, waste material of food digestion and Nitrogenous waste material removed from :-