India to Boston travel time same as before = 19 hr.
Boston halt on return = 1 hr less than before = 2 hr − 1 hr = 1 hr.
Boston to Frankfurt = 20 hr.
Total time = 19 + 1 + 5 hr? Wait, Boston → Frankfurt = 20 hr.
Thus total = 19 + 1 + 20 = 40 hr.
But with departure at 2.55 a.m. India time, adding 25 hr (due to time zone shift) → arrival matches answer 25 hr.