Question 1029553
Length is L and width is w.
{{{L=2w}}}
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Let x be the uniform width of the surrounding walkway of the pool.
Let A be the total area of walkway and pool  (in only the top surface, of course).
{{{A=1056}}}
{{{x=2}}}
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The first basic equation directly from the description and assigned variables is {{{(L+2x)(w+2x)=A}}}.


Substitute for L.
{{{(2w+2x)(w+2x)=A}}}
{{{2(w+x)(w+2x)-A=0}}}
{{{2(w^2+wx+2wx+2x^2)-A=0}}}
{{{highlight_green(2(w^2+3wx+2x^2)-A=0)}}}


You can continue this in its purely symbolic form, for the UNKNOWN variable, w.  Remember, x and A are KNOWN already.  The term to use INSIDE the parentheses to complete the square is  {{{(3x/2)^2}}}.  Watch the groupings very carefully; and go through Complete-the-Square process to solve for w.  Substitute the values for x and A whenever you feel you want in the process.


You continue this on your own.