We know that,
Number of days in the month of November = 30
Now, Date on which parcel was sent = 10th Nov.
Date on which it reaches the destination = 15th Dec.
Number of days taken in November = 30 - 10 + 1 = 21
Number of days taken in December = 14
So, total number of days taken by parcel to reach the destination = 21 + 14 = 35