Area of rectangle = Length x Width
We know that the area of the rectangle is 36 cm square and the width is 4 cm. So, the length will be 36/4 = 9 cm.
We know that the sides of square are equal and the area of the square = side x side.
From the figure, we can see that the side of the square = 5 cm.
Area of the square = 5 x 5 = 25 cm square
