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Question
A walkway of uniform width surrounds a circular pool.  The circumferences of the two have a difference of 22 feet.

Calculate width of the walkway.  

Note: Use pi = 22/7.

Thanks.

Answer
"A walkway of uniform width surrounds a circular pool."
You have two concentric circles. The radii of the inner and outer circles are r₁ and r₂, respectively.
https://www.flickr.com/photos/dwread/14417857432/
The width of the walkway is r₂ - r₁.

"The circumferences of the two have a difference of 22 feet."
2πr₂ - 2πr₁ = 22
πr₂ - πr₁ = 11
π(r₂ - r₁) = 11
r₂ - r₁ = 11/π = 11/(22/7) = 7/2 = 3.5
The width of the walkway is 3.5 feet.

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