Question

A rectangle lot 30m by 20m is surronded on all four sides by a concrete walk 3m wide. If you need to concrete only the sidewalk, how much concrete will you need? (surface area)

Answer 1

The length of the rectangle is 30 m

The width of the rectangle is 20 m

The sidewalk is 3m wide on all sides, so

length of sidewalk = 30+6 =36 m

Width of sidewalk = 20+6 = 26 m

Area of rectangle = $length*width$

Area of rectangle = $30\times20=600$

Area of rectangle including sidewalk = $36\times26=936$

Hence, area of sidewalk alone = area of rectangle with sidewalk -  area of rectangle

Surface Area = $936-600=336$ m²