Answer:
392ft²
Explanation:
We need to find out the area of the side walk .The area of the sidewalk will the difference of the areas of rectangles ABCD and EFGH .
The dimensions of rectangle EFGH is 35ft * 14ft
So it's area would be ,
A = l*b
A = 14ft * 35ft
A = 490ft²
Now the length of the rectangle EFGH will be,
l = 35ft + 2*3.5ft
l = 35ft + 7ft
l = 42ft
Again,its breadth will be,
b = 14ft + 2*3.5ft
b = 14ft + 7ft
b = 21ft
So it's area would be,
A = l * b
A = 42ft * 21ft
A = 882ft²
Therefore the area of the sidewalk will be,
ar(sidewalk) = ar(ABCD) - ar(EFGH)
ar(sidewalk) = 882ft² - 490ft2
ar(sidewalk) = 392ft²
and we are done!