Question 5 – BBP course book – Watson Co

Hi, I am struggling with question 5 from BBP course book and it is driving me crazy because I don’t understand what I am overlooking. The question says :
Watson Co acquired a property on 1 January 20X1 for USD 250000 for the building and $50,000 for the land. The building was estimated to have a useful life of 50 years. On 1 January 20X6 the property was independently valued which resulted in an increase of $100,000 to the carrying amount of the building and $50,000 to the carrying amount of the land. The useful life is unchanged.

What is the depreciation charge for the year ended 31 December 20X6?

My logic was the carrying value is now 280,000 / 45 remaining useful life, but that is wrong they are giving as an answer 280,000 / 44.

And I can’t figure out why? Does anybody know why this is 44 and not 45? Thanks in advance because it is driving me up the wall 🙂