A square DEFG of side 8 cm is inscribed in a rectangle of adjacent sides 20 cm and 16 cm as shown in the figure.

The area of the shaded portion is :

1. 64 cm²

2. 128 cm²

3. 256 cm²

4. 320 cm²

Area of shaded portion = Area of rectangle ABCD - Area of square DEFG

Area of square = Side²

Area of rectangle = Base x Height

Area of shaded portion = 20 x 16 - 8² cm²

= 320 - 64 cm²

= 256 cm²

Hence, option 3 is the correct option.