I wanna see a cow :^)

perimeter = 2l +2w, divide total perimeter by 2 for total length of 1 side and 1 width

172/2 = 86 (  total for 1 side and 1 width)

86-24 = 62 (since length is 24 ft longer subtract 24 then divide by 2 for width)

62/2 = 31

width = 31 feet

length = 31 +24 = 55 feet

check: 31*2 = 62, 55*2 = 110,  110+62 = 172

relief sculpture - images are set against a flat background.

a coin is a good example: the inscription, the date, and the figure are slightly raised above a flat surface. the ancient egyptians sometimes carved figures into a flat surface.  

pro: they take significantly less time to make and do not require as much tools or skills as free-standing

cons: not nearly as realistic, as it is not fully 3-d, and does not have the details that a free-standing one does.

freestanding sculptures (also called  carved in the round) are not attached to any  background.   they are 3-dimensional  and fully rendered.