Question 612490
<pre>
We'll first find the area of the top of the walkway in square feet
and then multiply that area by the the thickness of 4 inches, or
{{{1/3}}} ft to find the volume.  We'll find it in cubic feet and 
then convert to cubic yards.

The inner rectangle is 20ft×35ft, so it has an area of 700 sq.ft.  

The larger rectangle is 6 feet more on each dimension (since the
walkway is 3 feet more on each side of each dimension), so it is
26ft×41ft.  It has an area of 1066 sq. ft. This is the picture of 
the top of the walk. 

{{{drawing(800/3,400,-2,28,-2,43, locate(3.2,20.5,35),
locate(13,0,26), locate(-2,20.5,41), locate(13,5,20),
rectangle(0,0,26,41), rectangle(3,3,23,38) )}}} 

To find the area of the top of the walkway, we subtract the area
of the inner rectangle from the area of the larger rectangle.

Area of top of walkway = 1066 sq ft - 700 sq ft = 366 sq ft.

Since it is 4 inches thick, which is {{{1/3}}} ft, we find the 
volume by multiplying the area of the top of the walkway by the
thickness and get 366×{{{1/3}}} = 122 cubic feet.

Finally we must convert cubic feet to cubic yards.  There are 27 cubic
feet in 1 cubic yard, so we divide 122 by 27 and get 4.518518519
cubic yards.

Edwin</pre>