Question 1021078
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Pool 20 feet long and 12 feet wide, how wide is the safety walkway if the walkway area 228
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Your equation is 

(20 + 2x)*(12+2x) - 20*12 = 228,

where x is the width of the walkway in feet.

Left side is the difference of the areas of two rectangles.

Now simplify the equation:

{{{4x^2 + 2x*12 + 2x*20 + 20*12 - 20*12}}} = {{{228}}},

{{{4x^2 + 64x - 228}}} = {{{0}}}.

Reduce by the factor 4:

{{{x^2 + 16x - 57}}} = {{{0}}}.

Factor left side:

(x+19)*(x-3) = 0.

The roots are x = -19 and x = 3.
Only positive value does fit the condition.

<U>Answer</U>. The width of the walkway is 3 ft.
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