Question 984958
Is the rectangle the same thing as the pond?  Making sense of the description must permit these to be the same.


w width of pond
L length of pond
u the width of the WALK to surround the rectangular pond
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{{{L=w+12*cm*(1/2.54)(inch/cm)(1/12)(foot/inch)}}}
{{{L=w+12/(2.54*12)}}}
{{{L=w+1/2.54}}}
{{{L=w+0.3937008}}}------decimal approximation;
Are you sure that part of the description is 12 CENTIMETERS longer?
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A area of walkway alone;
A=160 ft^2
u=2


Total Area Pond Plus Walkway, {{{(w+2u)(L+2u)}}}
Area just the pond, {{{wL}}}
Just WALK area, {{{highlight_green((w+2u)(L+2u)-wL=A)}}}


Start simplifying that last equation difference being A.
{{{wL+2uL+2uw+4u^2-wL=A}}}
{{{2u(L+w)+4u^2=A}}}
{{{2u(L+w)=A-4u^2}}}
{{{highlight_green(L+w=(A-4u^2)/(2u))}}}, not yet finished symbolically...
You need to be sure about the description relating w and L, and when you are, you can readjust if necessary, and then continue, solving first ... for w.


If you meant what you described, then
{{{(w+0.3937008)+w=(A-4u^2)/(2u)}}}
{{{2w=(A-4u^2)/(2u)-0.3937008}}}
{{{highlight_green(w=(A-4u^2)/(4u)-0.19685)}}}, and just substitute the values to evaluate...