Question 1074313
x, the uniform width of walkway


{{{(6+2x)(9+2x)}}}, the combined area of upper surface of pond and the cement walkway



Walkway area and fish pond area are equal.
{{{(6+2x)(9+2x)=2*6*9}}}



{{{54+18x+12x+4x^2-2*6*9=0}}}

{{{27+9x+6x+2x^2-6*9=0}}}

{{{2x^2+15x+27-54=0}}}

{{{highlight_green(2x^2+15x-27=0)}}}
or as factored,
{{{highlight_green((2x-3)(x+9)=0)}}}


The sensible result is {{{x=3/2=1.5*meter}}}
Walkway is 1 and half meter wide.