Thank you foe the quick response mohamed, as far a I know that's should be 6 years and 8 Months. Why is that there is a deduction in the months?
I have another question. How about if you will subract it to a certain year :

20 years 5 Months 6 days
+ July 6, 2005
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( December 12, 2025 - 2400 days) <----- this here how will subtract this?