Question 1038000
Draw and label the rectangular figure.

<pre>
x     one of the pool's dimensions
y     the other pool's dimensions
w     uniform width extending from the two dimensions
A     Area of, ASSUMING the path and the pool combined
      (Your description does not specify which.)
-
x=12
y=8
A=224
w=unknown
</pre>


{{{highlight_green((x+2w)(y+2w)=A)}}}-----Solve for w.


{{{xy+2yw+2xw+4w^2=A}}}
{{{4w^2+(2x+2y)w+xy=A}}}
{{{4w^2+(2x+2y)w+xy-A=0}}}
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Formula for general solution of quadratic equation gives
{{{w=(-(2x+2y)+- sqrt((2x+2y)^2-4*4*(-A)))/(2*4)}}}


{{{w=(-2x-2y+- sqrt(4x^2+8xy+4y^2+16A))/(2*4)}}}


{{{w=(-2x-2y+- 2*sqrt(x^2+2xy+y^2+4A))/(2*4)}}}


{{{highlight(w=(-x-y+- sqrt(x^2+2xy+y^2+4A))/4)}}}
If neither of these two values work, then the other assumption may be what you really want; that the "area" is for JUST the concrete path.  That would change the initial equation a bit.