Question 330233
The area of the rectangle is 
{{{A=L*W}}}
{{{L=140+2W}}}
{{{A=(140+2W)W}}}
The area of the square is,
{{{A=s^2=60^2=3600}}}
Equate the areas,
{{{W(2W+140)=3600}}}
{{{2W^2+140W-3600=0}}}
{{{W^2+70W-1800=0}}}
Factor,
{{{(W+90)(W-20)=0}}}
Only the positive result makes sense here.
{{{W-20=0}}}
{{{W=20}}}ft.
{{{L=140+40=180}}}ft.