Assuming your figure is a rectangle: Length + width = half perimeter, in this case 20. Can we now find factors of 30 which total 20? Easy, 2 and 18! So the answer to the question is yes.
Presumably exactly as in the question
It all depends on the actual size of the space. Square footage is measured by multiplying the length of the space by the width. IE: a 6x6 space is 36sq feet.
8ft Wide by 8ft Long by 1ft Deep is 64sq/ft. A yard of sand is 36sq/ft. You will need a little less than 2sq/yards (72sq/ft). -------------------------------------------------------- We're talking about volume, not area, so 8x8x1 = 64 cubic feet, not sq. ft. A "yard" of sand actually means a cubic yard and is 3ft x 3ft x 3ft = 27 cubic feet, not 36 sq/ft. So you need 64/27 or a little over 2 1/3 cubic yards of sand.