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A children's park is 350 m long and 200 m wide. It is surrounded by a pathway of uniform width.
Suppose the total area of the park and the pathway is 74,464 m^2. How wide is the pathway?
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Your equation is
(350+2x)*(200+2x) = 74464,
where x is unknown width of the pathway.
The solution is x = 4 m.