Ans: 80 days
As he save Rs 2 per 3 days (3 + 3 - 4).
Rs 2 in 3 days
Rs 1 in = 3/2 days
Rs 54 in (3/ 2 )*54 = 78 day
As he deposited Rs 54 in 78days.
at 79th day he deposited 3 as usual = 54 + 3 = 57
at 80th day he deposited 3 as usual = 57 + 3 = 60
As he will only withdraw Rs 4 on 3rd days .. 81st day. which is not needed here, because he already have Rs 60 at 80th day.