a rectangle plot measure 20ft. by 30ft. A 3-ft.-wide sidewalk surrounds it. Find the area of the sidewalk.

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