Area of a rectangle = length (l) * width (w)
A = 30ft * 20ft
A = 600 sq ft
Now the width of a sidewalk that surroundeds it = 3 ft
so now the area of the rectangle with sidewalk= 30+3ft * 20+3ft
A = (33*23) ft
A = 759 sg ft
Area of the sidewalk = 759 - 600
A = 159 sq ft
