[Kamog]

If the initial # of potatos was X

After first man ate one third of the potatos, the remaining quantity is (2/3)X
After the second man ate one third of the remaining potatos, there are now (2/3)(2/3)X
After the third man ate one third of the remaining potatos, there are (2/3)(2/3)(2/3)X

(2/3)(2/3)(2/3)X = 8
X = 8(3/2)(3/2)(3/2)
X = 27 is the answer

27 potatos in beginning
First man ate 9 potatoes, then 18 remaining
Second man ate 6 potatos, then 12 remaining
Third man ate 4 potatos, then 8 remaining