The area of the path along one length is 4(2x)=8x^2,Their are two lengths so 8x^2 becomes 16x^2.
Now for the widths each is 4(8+x) this allows for the overhang of the path which wasn't included for the lenghts
so a width is 32^2+4x^2 again two widths so 32^2+4x^2 becomes 64^2+8x^2.
Overall area of path is 64^2+8x^2+16x^2=784sq/feet.
subtract 64 from both sides gives 24x^2=720.
divide both sides by 24 gives x^2=30sq/feet.
taking the square root of both sides gives x=30feet.
remember to check it back.
The sides 2*60*4=240*2(sides)=480.
The widths 4(30+8)=152*2(widths)=304.
Hope this helps (post what you got).