OK, so I would set all the money he has at first as X, our variable.

X - 1/3X - 120 = 2/3X - 120 is what he has after sentence 1

1/3(2/3X-120)-120 = 2/9X - 160 is what he has after sentence 2

1/3(2/9X - 160) -120 = 2/27X - 520/3 is what he has after sentence 3, but since by this time he doesn't have any money left, we can infer than

2/27X - 520/3 = 0, thus 2/27X = 520/3.

Find X to get the answer.